The National Basketball Association (NBA) is the major professional basketball league in the world, with teams from the United States and Canada. With the addition of the Toronto Raptors and the ancouver Grizzlies prior to the 1995～ 1996 season, the NBA expanded to 29 teams competing in two conferences, the Eastern and Western, in four separate divisions. Each team conducts a training camp in October to determine its 12- player roster. Training camp allows each team to evaluate players, especially rookies (first-year players), to assess the team"s strengths and weaknesses, and to prepare players for the upcoming season through a series of on-court drills and practice of offensive and defensive strategy. After a series of exhibition games, the NBA begins its 82-game regular season in the first week of November. (来源：专业英语学习网站 http://www.EnglishCN.com)
In the second week of February, the NBA interrupts its season to celebrate the annual NBA All-Star game, featuring the game"s best players as selected by the general balloting of fans throughout the United States and Canada. After the NBA season concludes in the third week in April, a total of 16 teams qualify for the playoffs11(8 teams from each conference). In each conference the two division winners are guaranteed a playoff spot. The remaining playoff spots in each conference are awarded on the basis of win-loss records to the six next-best teams, regardless of division. The playoffs start with the teams with better records playing the teams with worse records in a best-of-five series, in which the winner is the first team to win three games. In subsequent rounds best-of-seven series are played, with the first team to earn four victories win ning the round. The playoffs continue in this elimination scheme until a conference champion is crowned. The champions from the Eastern and Western conferences then meet in a best-of-seven series to determine the NBA champion.
Every June the league conducts its amateur draft, in which each team obtains the rights to the professional services of the best collegiate and international players. Any player who has graduated from high school and is at least 17 years old qualifies for the NBA draft if that player renounces intercollegiate eligibility. To determine the draft order the NBA uses a draft lottery, introduced in 1985. Those teams that failed to qualify for the playoffs the previous season are eligible for the lottery. The lottery determines the first three teams to select in the draft. The remaining teams draft according to their win-loss record of the previous season, so that teams with poorer records draft higher than those with better records. The NBA draft consists of only two rounds, with a total of 58 players chosen. Those players not selected in the draft can be invited to try out for a team and are sometimes signed to playing contracts.
The NBA"s official development league is the Continental Basketball Association (CBA). The league was founded in 1946 and now features 12 teams playing in two conferences. Many players, coaches, executives, and referees have honed their skills in the CBA before going on to NBA careers.