A Presidential election is something that happens every four years in the United States of America, as well as at other intervals in other countries. Basically, a whole bunch of liberals have good natured and intelligent debates back and forth for several months, and the intelligent, liberal public chooses which one of them they believe would do the best job leading the Executive Branch of the country for the next four years based on their track records and stance on important political issues.
At the same time, a group of loud, angry, drunken Republicans stand on stages that they buy with all the campaign contributions they get from tobacco and oil companies. They proceed to have a contest to see who can yell "Jesus" the loudest, and from that the uneducated conservative public picks whatever candidate they think looks best in an expensive suit.
After that, the two candidates engage in a year long battle between good and evil.
What also happens
A presidential election is a lying contest that occurs between several politicians backed by giant corporations. It is something that gives the illusion of choice in our government. It is merely a choice between the Authoritarian Right, and the somewhat less Authoritarian Right. Third party candidates never stand a chance. The only two parties that can ever win are the Democrats and the Republicans. The Democrats at least know how to pretend to be liberal, and sometimes enact laws that are somewhat liberal, more often occurring with social issues. The Republicans are blatantly evil, pandering to the wealthy elite and the ultra-religious, brainwashed masses.