The Lottery System
The NBA uses a weighted lottery system to determine the top three picks in the draft. The 14 teams that did not make the playoffs enter this lottery. Each team is assigned lottery balls based on their record, with the team that finished with the worst record getting the most balls and the best chance of winning the first overall pick. This system was created to prevent teams from intentionally losing games to get better draft picks.
How Lottery Odds Work
Each non-playoff team receives a certain number of lottery balls out of 1,000 total balls. The team with the worst record gets 250 balls, giving them roughly a 25 percent chance at the first pick. Teams with better records get fewer balls. During the lottery drawing, balls are randomly selected to determine which team gets picks 1, 2, and 3. The remaining 11 lottery teams then pick 4th through 14th based on their records, with the worst record picking 4th.
Playoff Teams in the Draft Order
The 16 teams that made the playoffs pick 15th through 30th in the draft. These teams are ordered in reverse of their playoff seeding. This means the lowest playoff seed (the 16th seed, or the 8th seed in the other conference) picks 15th, and the top seed picks 30th. This rewards the best regular season teams with later picks.
Why the Lottery Exists
Before 1985, the worst team automatically got the first pick, which created a problem. Teams would intentionally lose games late in the season to secure the first pick and a star player. The NBA created the lottery to discourage this practice. While the worst team still has the best chance to win the lottery, it is not guaranteed, making it less appealing for teams to tank.
Draft Order Adjustments
If a team acquired another team's draft pick through a trade, that pick follows the other team's place in the draft order, not the team that currently owns it. Additionally, teams that are penalized for salary cap violations or other infractions may have their draft picks moved to later rounds or forfeited entirely. 
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