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The NBA Development League is the official minor league development system for the NBA.  It features 16 teams, each with at least one direct affiliation to an NBA team.  Two teams, the Los Angeles Defenders and Austin Toros, are directly owned and operated by their NBA affiliate (the Los Angeles Lakers and San Antonio Spurs respectively). The remaining 14 teams have affiliation deals that are negotiated and managed by the D-League office.

Each NBA team is able to designate two players on its roster for assignment to the D-League.  This allows teams to develop young players and get them valuable in-game experience.  Teams may only designate players in their first or second year for assignment.

Notable previous assignment players include Pistons forward Amir Johnson, Lakers guard Jordan Farmar, and Bucks guard Ramon Sessions.  Assignments allow young players to get valuable playing time which may be limited on veteran clubs, as well as explicit coaching on areas of emphasis. 

In addition to assignment players, teams can also call-up free agents who are playing in the D-League.  The D-League provides a professional minor league with easy access for scouts and personnel, as well as a convenient way to track players' progress against NBA level talent. While it is certainly not the NBA, it is closer than any other minor league system available. Notable players with D-League experience include Jamario Moon, Kelenna Azabuike, Rafer Alston, Mikki Moore, and Ime Udoka.

Some NBA teams have fully embraced the D-League system and have used it to maximize their rosters' efficiency while developing their young talent to maximize their potential.  Some teams have gone so far as to purchase their own teams and install offensive and defensive systems similar to their own in their D-League squads.  Other teams have yet to fully embrace this system and question its usefulness and the quality of its players. 

For what it's worth, the six most active teams in the D-League are the Los Angeles Lakers, the San Antonio Spurs, the Detroit Pistons, the Boston Celtics, the Houston Rockets, and the Miami Heat.  Five of those teams were playoff teams.

Players cite the availability of playing time, additional practice, and concentrated development coaching as positives about the D-League.  Negative feedback of the league includes low salaries, hellacious travel schedules, and poor physical treatment resources.

The League plays a 50 game schedule starting in November and ending in April. It culminates with a three round playoff.  Last year's NBA D-League champion was the Idaho Stampede.