electoral college votesplitting.
Each state, proportionally to their populations gets a certain number of electoral college votes. Depending on which ticket wins in a given state, all of that state's electoral college votes goes to that particular ticket. The ticket with the most electoral college votes wins. And yes it is possible to win the presidency (most electoral college votes) but lose the "popular vote" (simple total of all votes cast in the country). It is one of those spots where Einsteinian physics starts to glare.
Electoral College rules are also State issues. According to this site, Nebraska and Maine allow their electoral votes to be split among candidates. But I don't think it has ever happened. Colorado had some sort of measure on the ballot to also allow splitting, but I don't think it passed. Persoanlly I think its agreat idea. If every state allowed splitting, the Electoral Vote would be much closer to the Popular IMO.
Steve G.