I saw on the news that Hillary Clinton won the popular vote but lost the election, how does this happen? I'm not familiar with the USA presidential election system.
Donald Trump won more than a majority of the electoral college votes. Each state has two plus the number of congressional districts votes in the electoral college. Trump won states worth a majority of that vote by small amounts.
Meanwhile, Hillary Clinton won states by larger amounts. For example, she won California and New York by large amounts. And she lost Texas, Florida, Pennsylvania, Michigan, and Wisconsin by small amounts.
The U.S. presidential elections work by an electoral college system. The simple version being that each state has a block vote based on its population which it allocates according to its own majority vote. For example, Texas gets 38 votes, New York gets 29 votes, et cetera (see this BBC page for details). In most states, each state gives all its votes to the plurality candidate in that state. So even if you win 48% of the vote in Texas the candidate who got 49% gets all 38 college votes.
Presumably the logic behind this is that the USA is a federal republic so indivdual states retain some degree of sovereignty and the fact that this system is embedded in the Constitution and so difficult to change.
Althogh this system can, in theory permit huge discrepencies between the popular vote and the electoral college this is aparently not the case this year as Trump has a clear majority in the Electoral College and a slim plurality in the popular vote.
She didn't. Yet.
Currently the popular vote is essentially tied (47.7%-47.5%. according to CNN). Both candidates have 59 million votes.
True, at the time of writing Clinton is ahead by less than 200,000 votes, however the amount that she is ahead by is a small fraction of the yet to be reported regular ballots, not to mention provisional ballots, votes disputed, and absentee ballots.
92% of regular ballots have been counted, which means that approximately 10,300,000 regular ballots have yet to be counted.
Having said that, here is information on the electoral college: