On Thursday, the Department of Justice is expected to release a redacted version of Special Counsel Robert Mueller’s summary of his team’s investigation into Russian interference in the 2016 presidential election and possible coordination with President Donald Trump’s campaign.

The Mueller investigation, as it’s known in shorthand, has been the center of the political universe for months but, since most Americans likely only visit that universe as tourists, the extent of its overlap with broader culture is certainly more limited.

With that in mind, here’s an overview of Thursday’s release, that covers the basic whos, whats, whens and whys for a framework for understanding a complex document and a complicated situation.

WHO’S INVOLVED

It’s important at the outset to establish the cast of characters. It’s worth skimming this section just to have a sense of who everyone is, but you should consider it more of a glossary for use in the rest of the document. People who worked directly with Trump’s campaign are highlighted.

The investigators:

–Special counsel Robert Mueller. Mueller served as FBI director under Presidents George W. Bush and Barack Obama. He retired in 2013. In May 2017, he was asked by Deputy Attorney General Rod Rosenstein to serve as special counsel to investigate possible collusion between Russia and the Trump campaign.

–Attorney General William Barr. Barr has been the head of the Department of Justice since his confirmation in February. In that role, he has authority over Mueller’s investigation.

–Former Attorney General Jeff Sessions. Sessions served as Trump’s original attorney general until he was dismissed in November. In March 2017, he recused himself from involvement in investigations into the Trump campaign and possible overlap with Russia because of his work with the campaign during 2016.

–Deputy Attorney General Rod Rosenstein. Rosenstein was appointed by Trump and confirmed to the Justice Department’s No. 2 job in April 2017. After Sessions’ recusal, Rosenstein became the department’s senior official on the Russia investigation.

–Former FBI Director James Comey. Comey took over the FBI after Mueller’s retirement. He served until his dismissal in May 2017 by Trump.

THOSE BEING INVESTIGATED

–President Trump

–Donald Trump Jr. Trump’s eldest son. He worked closely with the Trump campaign and runs the Trump Organization.

–Jared Kushner. Trump’s son-in-law, the husband of Trump’s daughter Ivanka Trump. Kushner was a real estate developer before joining Trump’s campaign effort and, after his victory, joining the administration.

–Paul Manafort. Manafort was a longtime political consultant and lobbyist in Washington, D.C., before being tapped in late March 2016 to help Trump’s campaign. He eventually ran the effort, serving as Trump’s campaign chairman until he was fired in August 2016 after details about his work for a pro-Russian political party in Ukraine came to light.

–Rick Gates. Gates worked with Manafort at his lobbying firm before both joined the Trump campaign. Gates eventually served as deputy campaign chairman, before then helping Trump’s inaugural committee after Trump’s victory.

–Michael Flynn. Flynn, a former Defense Department official under Bush and Obama, joined Trump’s campaign early in 2016. He went on to briefly serve as Trump’s national security adviser.

–George Papadopoulos.A consultant in the oil and gas industry, Papadopoulos was named in March 2016 as a member of Trump’s foreign-policy advisory team.

–Roger Stone.Stone is a longtime political activist and former business partner of Manafort’s who for a long time provided political advice to Trump. He briefly worked directly with the campaign during 2015.

–Michael Cohen. Trump’s personal attorney from 2007 until last year.

–Russia. This is an admittedly broad group. Of particular interest to investigators were two groups of Russians:

The group of Russians alleged to have hacked the email accounts of the Democratic National Committee and Hillary Clinton’s campaign chairman in 2016. This group is believed to work for Russia’s intelligence service.

The group that orchestrated an effort on social media to influence American voters and foster political disagreement.

–“Guccifer 2.0.” One of the personas used to distribute information stolen from the DNC during 2016. It’s believed that the persona was controlled by an individual tied to Russian intelligence.

–WikiLeaks. The document-sharing organization was eventually responsible for the dissemination of the bulk of the hacked information.

THE OTHERS

The names below are listed in alphabetical order by last name.

–Aras and Emin Agalarov. The Agalarovs are a family of developers in Moscow. They partnered with the Trump Organization in 2013 to host the Miss Universe pageant when it was owned by Trump. Emin Agalarov is also a pop singer.

–Rinat Akhmetshin. A lobbyist who at one point worked with a military unit linked to the Soviet Union’s intelligence service.

–Julian Assange. The founder of WikiLeaks. During the 2016 election, he was living in Ecuador’s embassy in London after seeking asylum there in 2012.

–Maria Butina. A college student and gun activist who last year admitted to working on behalf of the Russian government. She worked closely with Torshin.

–Hillary Clinton. The Democratic candidate for the presidency in 2016.

–Sam Clovis. Clovis is a longtime political activist from Iowa who joined the Trump campaign in August 2015. He eventually led the campaign’s foreign policy advisory team.

–Jerome Corsi. A conservative writer and conspiracy theorist who was associated with Roger Stone.

–Randy Credico. A New York-area radio host who was also associated with Stone.

–Democratic National Committee. The DNC is the official organization housing the Democratic Party.

–Rob Goldstone. A British music promoter who represents Emin Agalarov.

–J.D. Gordon. A campaign adviser who worked with the foreign policy team.

–Stefan Halper. A professor at Cambridge University who also worked as an FBI informant during the 2016 campaign.

–Konstantin Kilimnik. A Russian-born aide to Manafort’s lobbying work with reported ties to Russian intelligence.

–Sergey Kislyak. Russia’s ambassador to the United States.

–Joseph Mifsud. A British professor with alleged links to the Russian government.

–Carter Page. Page, like Papadopoulos, was tapped to serve on Trump’s foreign-policy advisory team in March 2016. He had already attracted attention from the FBI several years earlier when a wiretap picked up a suspected Russian agent naming Page as a possible target for recruitment.

–Dmitry Peskov. Spokesman for Russia’s president.

–Richard Pinedo. A businessman who illegally provided valid bank account numbers to individuals.

–John Podesta. Clinton’s campaign chairman.

–Russian President Vladimir Putin.

–Felix Sater. A longtime business partner of Trump’s with whom he worked on several development projects, including the onetime Trump Soho hotel in Lower Manhattan.

–Alexander Torshin. A Russian politician and lifetime member of the NRA.

–Alex van der Zwaan. An attorney who worked with Manafort and Gates on their Ukraine work.

–Natalia Veselnitskaya. An attorney who, among other things, works to overturn sanctions imposed on Russia by the Obama administration. She’s linked to Russia’s government.

HOW THE INVESTIGATION STARTED

Over the course of the 2016 campaign, federal investigators began noticing a number of links between members of Trump’s campaign and Russia.

There was Manafort, who had links to Russian oligarchs and to pro-Russian politicians in Ukraine. There was Page, who traveled to Russia in July 2016 to give a speech and who was already on the FBI’s radar. There was Flynn, who’d traveled to Moscow for a dinner in December 2015, sharing a table with Putin.

And then there was Papadopoulos. In July 2016, after WikiLeaks started publishing files stolen from the DNC, the Australian government reached out to U.S. officials. It turns out that Papadopoulos had told an Australian diplomat in May 2016 that he’d heard Russia had dirt on Clinton – a comment that seemed to be bolstered by the WikiLeaks releases. That information spurred the launch of Crossfire Hurricane, the FBI’s investigation into the Trump campaign’s possible links with Russia on July 31.

Part of the investigation involved the use of Halper to collect information. He had interactions with Page, Papadopoulos and Clovis during the campaign. In October, after Page had left the campaign, he was targeted with a federal counterintelligence surveillance warrant.

The FBI’s investigation continued over the course of the campaign, with FBI agents debating how forcefully to push on the probe. It continued after Trump won – at which point it was first reported in the news media.

Once Trump was inaugurated, he saw the investigation as a “cloud” overhanging his presidency. After reportedly pressuring Comey to end an investigation into Flynn and asking Comey to help lift that cloud, Trump fired Comey on May 9, 2017. Eight days later, Rosenstein, apparently worried about protecting the investigations into Trump’s campaign, appointed Mueller – moving the probe largely (but not entirely) out of Trump’s grasp.

Mueller’s mandate was to, first, identify any links or coordination between Trump’s campaign and the Russian government and, second, to investigate anything that “arose or may arise” from that investigation. That eventually included a look at whether Trump had tried to unlawfully derail the investigation.

The probe was soon distilled to those two primary issues: Possible collusion with Russia by Trump’s campaign and possible obstruction by Trump. Russia’s involvement in the campaign was similarly reduced to two main components: The hacking and distribution of stolen information and the simultaneous effort to influence Americans on social media and through public events.

Last month, Mueller completed his work.

WHAT’S BEING RELEASED NOW?

After Mueller (and his team of lawyers) completed their investigation, they sent a report, several hundred pages long, to Barr, as the regulations creating a special counsel dictate. It is expected to include explanations of why Mueller chose to indict some individuals (see below) and why he decided not to indict others.

After Mueller turned his report over to Barr, Barr released a four-page letter providing a summary of the two questions identified above. The probe, Barr said, quoting Mueller, had “not establish[ed] that members of the Trump Campaign conspired or coordinated with the Russian government in its election interference activities.” As for obstruction, Mueller’s team did “not conclude that the President committed a crime, it also does not exonerate him,” as Mueller’s report is quoted. Barr and Rosenstein, though, determined that there was insufficient evidence to constitute an obstruction-of-justice crime.

This summary was used by Trump and his supporters to argue that he’d been cleared on both the charge of collusion and any obstruction of justice. That’s not the case.

Barr’s letter never addressed “collusion,” a loosely used (and not legally defined) term that means different things to different people. Instead, Mueller found insufficient evidence to establish that Trump’s team had coordinated with the Russian government. On obstruction, Mueller’s “does not exonerate” speaks for itself. What’s more, Barr’s letter suggests that the evidence on obstruction includes some material that is still not public.

It may become public with the release of the redacted report on Thursday. What’s expected to be published is what Mueller gave Barr, those 300-plus pages of information – but only after Barr and the Justice Department have scrubbed out material that needs to be protected because it involves grand jury work or information related to ongoing investigations. There’s some question about how extensive those redactions will be, particularly given Barr’s history on such matters.

In other words: We probably still won’t know everything that Mueller established once the redacted report is out.

WHAT WE ALREADY KNOW

That said, we already know a lot. In February, we looked at the fact that Mueller had already published hundreds of pages of material related to existing indictments and plea deals.

The numbers that we already know about are big: 2,800 subpoenas, 500 witnesses, 500 search warrants leading to nearly 200 individual criminal counts obtained against more than 30 people. Admissions of guilt by six people and outstanding indictments covering identity theft, money laundering, obstruction, witness tampering, lying to investigators and conspiracy.

Even beyond the demonstrated and alleged criminal conduct, we’ve also learned a lot about how and where Trump’s team and Russian actors overlapped. Here’s how it breaks down.

EXISTING INDICTMENTS ASND COOPERATION DEALS

The following individuals have been charged with crimes or admitted to guilt. They’re listed in chronological order. There are some details about events included below that are more fully explained later in this article.

–Oct. 5, 2017: Papadopoulos admitted to lying to investigators about when he met Mifsud, the Russia-linked professor who told him that Russia had Clinton emails – and that he lied about when he learned about those emails. (It was this information that Papadopoulos later shared with the Australian diplomat.)

–Oct. 27, 2017: Manafort and Gates were indicted on a range of crimes focused on their work lobbying for foreign organizations and individuals.

–Dec. 1, 2017: Flynn admitted to having lied to investigators about conversations with Ambassador Kislyak the previous December. Flynn claimed not to have discussed sanctions with Kislyak which intercepted communications involving Kislyak appear to have contradicted.

–Feb. 12, 2018: Pinedo admits to charges of identity fraud for having provided bank account numbers to people who he later learned were part of Russia’s social-media interference effort.

–Feb. 16, 2018: Three Russian companies and 13 Russian individuals are charged with participating in that effort through an organization called the Internet Research Agency. The effort before the election involved spreading divisive messages on social media (including through paid ads) and promoting events supporting Trump. Some of the work at those events was done by Americans paid through PayPal accounts that were created using Pinedo’s bank-account numbers. There remains no evidence that this effort included any sophisticated targeting of American voters.

–Feb. 20, 2018: Van der Zwaan admits to lying to investigators about his interactions with Gates and Manafort during a period that preceded the campaign.

–Feb. 22, 2018: Gates and Manafort face a flurry of new charges, centered on financial crimes. Gates quickly flips and agrees to help the investigation.

–June 8, 2018: Manafort and Kilimnik face new charges alleging that they tried to obstruct Mueller’s investigation. The next month, Manafort goes to trial in Virginia on a number of the above charges and is convicted on eight before also deciding to flip.

–July 13, 2018: Mueller obtains a lengthy indictment outlining how 12 people allegedly working for Russian intelligence gained access to the DNC network and Podesta’s email account (among other hacks) – and how some material was then passed to WikiLeaks.

–Sept. 14, 2018: After admitting to eight criminal charges centered on fraud and campaign finance violations, Cohen also admits to lying to congressional investigators about the duration of a proposed deal he was working on with Sater to build a Trump Tower Moscow. The campaign finance charges also implicate Trump.

–Jan. 25, 2019: Stone is indicted on a charge of lying to investigators and attempting to obstruct the investigation.

WHERE RUSSIAN AND THE CAMPAIGN OVERLAPPED

When Trump sat down with NBC News’ Lester Holt shortly after the Comey firing, he made a claim that he’s repeated hundreds of times since: There was no collusion with Russia.

The accuracy of that statement depends on how you use the word “collusion,” which can vary wildly. What’s unquestioned is that there were numerous points at which Trump’s campaign was directly or indirectly linked to Russian actors and/or Russia’s two-pronged effort to interfere in the election.

Those connections include the following.

–The Trump Tower meeting. In June 2016, Trump Jr., Manafort and Kushner met with the Kremlin-linked attorney Veselnitskaya and her colleague Akhmetshin at Trump Tower.

The meeting was orchestrated by Goldstone on behalf of Emin Agalarov. Goldstone’s initial email suggested that the meeting was to share derogatory information about Clinton as part of the Russian government’s support for Trump. Trump Jr. infamously replied, “[I]f it’s what you say I love it.” Agalarov would later claim that he and Trump Jr. spoke about the meeting in advance.

Cohen claims that he was present when Trump Jr. informed Trump in early June that a meeting was set, a reference, he believes, to the Trump Tower meeting. Trump has denied knowing about the meeting in advance, including, according to CNN reporting, in his written responses to questions from Mueller’s team.

The meeting ended up centering on the issue of Russian sanctions according to attendees and to contemporaneous notes taken by Manafort.

–Manafort passing poll data to Kilimnik. One of the most enticing allegations is that Manafort gave Kilimnik (who, remember, is believed to have ties to Russian intelligence) dozens of pages of proprietary polling information from the Trump campaign. It’s believed this happened at a meeting near Trump Tower in early August 2016. The interaction was described by one Mueller attorney as getting “very much to the heart of what the special counsel’s office is investigating.”

There’s no public evidence, though, that Manafort was sharing that information to aid Russia’s interference effort. He’d previously contacted Kilimnik seeking advice on how to leverage his position with Trump’s campaign to be repaid by Russian business executives with whom he’d formerly worked; the poll data may have been part of that effort.

–The Papadopoulos-Mifsud connection. In addition to being told by Mifsud that Russia had dirt on Clinton, Papadopoulos also worked with an official connected to the government on setting up a meeting between Trump and Putin. That meeting didn’t happen.

–Various possible connections to WikiLeaks. Both Donald Trump Jr. and Roger Stone interacted privately with WikiLeaks during the campaign, during the period between the organization’s July release of DNC data and its October dump of Podesta’s emails. In neither case did those interactions amount to anything suggesting significant coordination.

Stone, though, repeatedly hyped his own connections to WikiLeaks. As early as the spring of 2016, Stone was claiming to have spoken with WikiLeaks’ Assange about its leaks. Shortly before the July release, Cohen claims to have heard a phone call in which Stone told Trump that a release was coming; after the information was published a campaign official was asked – by who isn’t clear – to reach out to Stone to see what else WikiLeaks had. Stone contacted Corsi who contacted a writer living in London.

Over the summer, Stone kept claiming a link to WikiLeaks, a claim that was bolstered when radio host Credico interviewed Assange and began texting with Stone about what WikiLeaks might be doing. It remains unclear how much any of these people actually knew about what WikiLeaks was doing and how much was bluster. There’s no strong indication in any case that it was the former.

Stone also had an apparently brief exchange with “Guccifer 2.0″ though that also doesn’t appear to have resulted in any significant coordination.

–Torshin’s outreach to the campaign. Torshin, the NRA-linked Russian politician, repeatedly tried to contact the campaign through intermediaries in the spring of 2016. That outreach was apparently blocked – but he ended up meeting Trump Jr. briefly at an NRA event in Kentucky in late May.

Torshin was also working with Butina who had a close relationship with Gordon late in the campaign.

–Page’s interactions in Moscow. While in Moscow in July 2016, Page spoke with a deputy prime minister who, he told the campaign in an email, “expressed strong support for Mr. Trump.” Page was identified in the dossier of reports compiled by former British intelligence officer Christopher Steele as having more robust conversations with Russian actors, but those reports remain largely unsubstantiated.

–Cohen’s contact with Putin’s team. As part of his effort to advance the Trump Tower Moscow deal with Sater, Cohen contacted Putin’s spokesman Peskov. In January, he had an extended conversation with someone from Peskov’s office aimed at facilitating the project. The project apparently fizzled out in June as Sater was pushing to get Cohen and Trump to travel to Russia.

–Various interactions with Kislyak. Several Trump campaign staff and advisers, including Sessions and Kushner, also met with Kislyak before the election. After the election, there were more contacts, including Flynn’s calls with the ambassador.

WHERE TRUMP MIGHT HAVE TRIED TO INFLUENCE PROBE

We also already know about a number of points where Trump appears to have wanted to influence or derail the investigation into Russian interference and his campaign.

–Trump’s interactions with Comey. Comey and Trump first met on Jan. 6, 2017, at Trump Tower, when Comey and other officials briefed the then-president-elect on Russia’s interference efforts. Once Trump was inaugurated he repeatedly – according to Comey – tried to get Comey to lighten the burden of the Russia investigation. That included pressuring him to “lift the cloud” the investigation posed and not pursuing charges against Flynn.

It was Comey’s firing that ultimately spurred the appointment of Mueller, apparently out of concern that the investigation was threatened.

–Trump’s response to the Trump Tower meeting story. When in July 2017 the New York Times contacted the White House after learning about the June 2016 meeting, Trump himself crafted a statement responding to the paper’s questions which was quickly revealed as woefully incomplete. In a conversation with his legal team’s spokesman, Trump’s senior aide Hope Hicks allegedly told the spokesman that the emails from Goldstone showing the statement to be false would never come out. (Hicks denies this.)

–Trump’s threats to fire Mueller, Sessions or Rosenstein. At various points, Trump seemed to toy – both publicly and privately – with the idea of firing several of those at the heart of the Russia probe. That includes Sessions, who he actually did fire last November. These threats might have had the intentional or unintentional effect of putting pressure on investigators.

–Trump’s tweets threatening or praising potential witnesses against him. As the Mueller probe wound on, Trump would express his views about it and its participants on his Twitter account. As Cohen moved to cooperate with investigators and, later, as Stone faced potential charges, Trump weighed in on those actions in ways that some experts felt amounted to possible attempts at witness tampering.

There also exist outstanding questions about when Trump or his team may have discussed possible pardons with potential witnesses against him.

WHAT WE DON’T ALREADY KNOW

Well, a lot. Some of the most immediate questions, it seems, are those below.

–What did Trump know and when did he know it? Mueller and his team were looking at a specific question through a legal lens. Trump’s denials of knowing about the Trump Tower meeting, for example, may have limited legal importance – but huge political importance, given his repeated public denials of knowing about the meeting.

–Even if it didn’t rise to criminal coordination, how robust were the links between Trump’s campaign and Russia’s outreach? This gets to the question of “collusion” and is itself politically important. Mueller found some evidence of connections, obviously. Were they any more robust than what’s already known.

–What was the point of Manafort sharing polling information with Kilimnik? Was the point to get that data back to the Russian government?

–What’s the evidence of obstruction that isn’t public? In Barr’s letter outlining what Mueller determined, he wrote that the report “addresses a number of actions by the president – most of which have been the subject of public reporting – that the Special Counsel investigated as potentially raising obstruction-of-justice concerns.” What are those components that haven’t been the subject of public reporting?

–Who were the 500 witnesses that were interviewed, and why? Some of these we know. But knowing the full scope of the investigation would help answer questions about where Mueller was looking.

–Why wasn’t Corsi charged? Late last year, Corsi publicized a proposed plea agreement from Mueller in which he’d admit to lying to investigators. He didn’t accept the deal – but also wasn’t charged. Why not?

It’s very possible, given the expected redactions that we won’t learn the answers to any of these questions.

In part that’s because of a tenet about sharing information that was presented by Rosenstein earlier this year. The Justice Department won’t generally publish information that’s derogatory about someone who isn’t going to face criminal charges. That might mean heavy redactions centered on people like Trump Jr. and Kushner which keep certain details of what happened hidden.

At the extreme end of the spectrum, it could mean a near-total blackout on information about Trump who, under Justice Department regulations can’t face charges as a sitting president.

WHAT HAPPENS NEXT?

A few things.

First, there will be a concerted effort to make public the redacted portions of Mueller’s report. That fight is likely to end before a judge.

Then, congressional Democrats will have to decide how much to fight over this issue. If the case for obstruction seems more robust than Barr’s letter would have made it seem, is an impeachment effort warranted? Are there new lines of inquiry posed by Mueller’s findings, as there were when Cohen testified before Congress?

One thing that possibly won’t happen next is Americans suddenly changing their minds about Trump. Shortly before Mueller completed his work, Fox News asked Americans how likely it was that his final report would change their minds. Most Americans said the odds their views of Trump changing were at best small.

But, then, we’ll have to see the report to assess if that’s true.