QAnon is a conspiracy theory that revolves around Donald Trump’s presidency. The QAnon or "Q Anonymous" conspiracy started on the 4chan messageboard where an anonymous post by someone reportedly high up in the government started the conspiracy off. The basis of the theory is that the Mueller Investigation and report is a cover up to hide the “real” investigation into the child sex ring being run by current and former high level government employees, such as Hilary Clinton.
The conspiracists believe that the “Pizzagate” conspiracy was real and further evidence is going to be uncovered in the “real” investigation that is still happening behind closed doors. The “Pizzagate” conspiracy was that Hilary Clinton was operating a child sex trafficking ring out of the basement of a pizza parlour called Comet Pizza. The only problem is that Comet Pizza doesn’t have a basement as one person found out when they came to investigate for themselves with a weapon in October 2016. Luckily no one was injured in this incident. It does, however, show the dangerous potential of these types of lies.
QAnon conspiracy theorists put a lot of emphasis on the clues “given” by Trump. They believe that he gives them clues about the ongoing nature of the investigation by giving specific numbers and phrases in speeches. They pay particular attention to the number 17, as Q is the 17th letter of the alphabet. They believe messages are still being posted on 4chan from either the OP or someone else close to the information. These are all anonymous though (as all posts on 4chan can be) so there’s no proof that the OP has kept updating 4chan or that the original Q was ever really an employee of the government.