Minor League Baseball is a hierarchy of professional baseball leagues in the Americas that compete at levels below Major League Baseball (MLB) and provide opportunities for player development and a way to prepare for the major leagues. All of the minor leagues are operated as independent businesses. Most are members of the umbrella organization known as Minor League Baseball (MiLB), which operates under the Commissioner of Baseball within the scope of organized baseball. Several leagues, known as independent baseball leagues, do not have any official links to Major League Baseball.

Except for the Mexican League, teams in the organized minor leagues are generally independently owned and operated but are directly affiliated with one major league team through a standardized Player Development Contract (PDC). These leagues also go by the nicknames the "farm system", "farm club", or "farm team(s)" because of a joke passed around by major league players in the 1930s when St. Louis Cardinals' general manager Branch Rickey formalized the system, and teams in small towns were "growing players down on the farm like corn."

Minor leagues are professional sports leagues which are not regarded as the premier leagues in those sports. Minor league teams tend to play in smaller, less elaborate venues, often competing in smaller cities. This term is used in North America with regard to several organizations competing in various sports. They generally have lesser fan bases and smaller budgets.

The minor league concept is a manifestation of the franchise system used in North American sports, whereby the group of major league teams in each sport is fixed for long periods between expansions or other adjustments, which only take place with the consent of the major league owners. In England (and many other countries), the football leagues have many divisions below the top-flight as part of the football pyramid. In other parts of the world there is usually either a system of annual promotion and relegation, meaning that clubs have no fixed status in the hierarchy, or there is only one professional league per country in each sport, rendering the major/minor distinction irrelevant.

Minor hockey is an umbrella term for amateur ice hockey which is played below the junior age level. Players are classified by age, with each age group playing in its own league. The rules, especially as it relates to body contact, vary from class to class. In North America, the rules are governed by the national bodies, Hockey Canada and USA Hockey, while local hockey associations administer players and leagues for their region. Many provinces and states organize regional and provincial championship tournaments, and the highest age groups in Canada also participate in national championships.

Minor hockey is not to be confused with minor league professional hockey.

Canada

In Canada, the age categories are designated by each provincial hockey governing body based on Hockey Canada's guidelines, and each category may have multiple tiers based on skill.

Age categories

To qualify in a category, the player must be under the age limit as of December 31 of the current season.