The Electoral College awards each state a number of electors equal to its congressional delegation (House + Senate). Forty-eight states allocate all their electors to the statewide winner; Maine and Nebraska allocate by congressional district. A presidential candidate needs 270 of 538 electors to win.
Five times in U.S. history (most recently 2000 and 2016), the popular-vote winner lost the Electoral College. Reform proposals include the National Popular Vote Interstate Compact (NPVIC), which would commit member states to award their electors to the national popular-vote winner once enough states (270 EVs) have signed on.
Defenders argue the Electoral College preserves federal balance, prevents urban-area dominance, and forces candidates to build geographically broad coalitions. Critics argue it makes most votes irrelevant, distorts campaigns toward swing states, and can produce winners who lost the national vote.