This is a question that can and should be directed to the Trump White House.
But here's a succinct answer, based on what Q him-/herself claims:
QAnon, often called just “Q,” is someone with Q-Level security clearance and a history of Military Intelligence working within the Trump administration to disseminate information to the American people directly.
As for the specific identity of Q – no one really knows for sure (save for a few people in the actual Trump administration). And while I just kind of implied that Q is an individual, in fact, it’s clear that Q works with a team of individuals in the intelligence community, and there may be more than one person on that team posting as Q.
