The NFL regular season is a seventeen-week schedule during which each team plays sixteen games and has one bye week. The season currently starts on the Thursday night in the first full week of September (the Thursday after Labor Day) and runs weekly to late December or early January. At the end of each regular season, six teams from each conference play in the NFL playoffs, a twelve-team single-elimination tournament that culminates with the championship game, known as the Super Bowl. This game is held at a pre-selected site which is usually a city that hosts an NFL team. Selected all-star players from both the AFC and NFC meet in the Pro Bowl, which in 2010, took place a week prior to the Super Bowl, at Sun Life Stadium in Miami Gardens, Florida

a 4-game exhibition season (or preseason) running from early August to early September;
a 16-game, 17-week regular season running from September to December or early January; and
a 12-team Single-elimination playoff beginning in January, culminating in the Super Bowl in early February.
Traditionally, American high school football games are played on Friday, American college football games are played on Saturday, and most NFL games are played on Sunday. Because the NFL season is longer than the college football season, the NFL schedules Saturday games and Saturday playoff games outside the college football season.

. From Wikipedia