In an organized sports league, a typical season is the portion of one year in which regulated games of the sport are in session: for example, in Major League Baseball the season lasts approximately from the last week of March to the last week of September. In other team sports, like association football or basketball, it is generally from August or September to May although in some countries – such as Northern Europe, North America or East Asia – the season for outdoor summer sports starts in the spring and finishes in autumn, mainly due to weather conditions encountered during the winter.

A year can often be broken up into several distinct sections (sometimes themselves called seasons). These are: a preseason, usually a series of exhibition games played for training purposes; a regular season, the main period of the league's competition; the postseason, a playoff tournament played against the league's top teams to determine the league's champion; and the offseason, the time when there is no official competition.

In association football, many clubs tour and then they have a series of exhibition games for training purposes. Specifically in Brazil, teams play in state championships before the start of the Brazilian League.

In baseball, many clubs go to spring camp and then they have spring training.

In gridiron football, the National Football League's preseason and the Canadian Football League's preseaon are highly structured three– or two–game series of games, respectively, in which teams are afforded a larger roster limit and play games that do not count toward their records; they are used to evaluate and prepare talent for the upcoming regular season. In college football, particularly that played at the FBS level, a true preseason is not played but many teams play a "spring game" which is an internal team practice structured like a game.

In the highest levels of professional tennis, the preseason (November–December) consists of extensive period of training on and off the court (gym/fitness work as well as working on tennis-specific skills like for example improving the accuracy of serve).

In sport, the term "regular season" or "home-and-away season" refers to the sport's league competition. The regular season is usually similar to a group tournament format: teams are divided into groups, conferences and/or divisions, and each club plays a set number of games against a set number of opponents. In most countries the league is played in a double round-robin format, where every team plays every other team twice, once at their home venue, and once away at the opposition's venue as visitors. The results over all games are accumulated and when every team has completed its full schedule of games, a winner is declared.

In North America, the scheduling is different. Rather than every team playing all others twice, teams usually play more games against local rivals than teams in other parts of the country. For example, the NBA's Los Angeles Lakers will play the Los Angeles Clippers (a team within their division, a subdivision of the conference) four times in a regular season, while both will only play the Toronto Raptors, who are in the opposite Eastern Conference, twice. Part of this is due to the vast geographic distances between some teams in North America—measured in a straight line, Los Angeles is 3,494 kilometres from Toronto, for instance—and a desire to limit travel expenses. In the scheduling system used in the NFL, it is possible for two teams to only meet every four years, and to only have 2 common opponents in a season. Major League Baseball has the most uneven schedules of all the four major North American sports. In MLB, the conferences are called leagues instead, but have exactly the same effect as conferences (as with all North American major leagues, leagues, conferences, and division are not based on skill, but instead geography, history, and rivalries). Prior to scheduling changes in 2023, teams played 19 games against each of the teams in their own division each year but only played 20 games total against all of the teams in the other league. Because each of the inter-league match-ups was part of a 3-game series or a 2-game series, teams played no games at all against most teams from the other league. They played 6 of the 15 teams in the other league, a historically high number (until 1997, interleague play was limited to exhibition matches and the postseason World Series, and thus MLB teams did not play the other league's teams at all). In 2023, teams played all interleague teams in a single season for the first time; teams now play a 3-game series against all teams, except their designated interleague rival with 4 games, totalling to 46 games (later increased to 48 games and a 6-game series with their interleague rival for the forthcoming 2025 season).