The president leads the nation, making suggestions to Congress about laws and working closely with them to get them passed or rejected. They are also commander in chief and have a huge role in shaping relationships with other countries.
As head of the executive branch, the President carries out the day-to-day administration of the Federal Government, supervising 15 executive departments (led by members of the Cabinet). They are responsible for execution and enforcement of laws created by Congress, which means they often shape the nation’s domestic agenda.
The President also negotiates with foreign governments on behalf of the United States, although the Constitution limits their authority to what Congress lays out in the treaties and agreements they can make. They also have substantial authority to direct military strategy.
In addition to their presidential duties, the President is leader of their party. This is important for public support, and if they do well in their role the president is likely to be rewarded in the next elections.
In some cases, more people across the country vote for one candidate but that person is not elected to the presidency because the other person gets a larger number of electoral votes. This happens because the electoral college system is set up in a way that allows small, highly-populated states to have more influence in who wins the election. This has happened five times. It’s a controversial aspect of the presidency and has caused many to propose constitutional amendments on the subject.