If you've voted in past U.S. elections or have taken a history class, you'll have an idea of what the Electoral College is. The centuries-old system has states appoint a number of electors equal to the number of representatives they have in Congress to the Electoral College. From there, all the states (except for Maine and Nebraska) utilize a winner-take-all system in which the candidate who wins the most votes earns all of the state's Electoral College votes.
From there, whichever candidate has 270 out of 538 of the electoral votes wins the election. Sounds simple, right? Well, it gets a little more complicated.
Most years, we have an idea of who won by the end of election day, based on the results that are available, but the outcome of any election isn't final on election night. In fact, it isn't set in stone until all the electors meet to count the electoral votes and declare the results. This meeting, where the electoral votes are counted, won't happen until January 6, 2021.
What happens then: The sitting vice president takes on the role of Senate president and officiates the joint session of Congress. They ask electoral members to read aloud the results of their representing state's certificates cast by the electors to finalize the vote count. If nobody objects to any of the readings, the Senate president officially announces the chosen president-elect and vice president-elect from the election.
And then it's official—or at least it is when the two winners are inaugurated on January 20, 2021, by the United States Supreme Court's Chief Justice. So, if there's anything to take away from this, it's that while you'll hear a lot about who "won" the election, nothing will be completely official until January.