system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How does the NBA draft work?

I'm Australian and drafts aren't done over here so it's a completely foreign subject. Over here, teams just offer people a place on spot much like you might be offered a job in the real world.
gpt
The draft exists in the interest of competitive balance. The NBA wants all 30 of its teams to offer a product to fans worth selling, and that can't happen if incoming players are free to sign contracts with whichever team they want. The good players would be more likely to sign with teams that are already good, or teams that are in bigger markets. The skill gap between the top 5% of NBA players and the bottom 95% is simply too large to allow all the best players to go on a few teams.

So the basic idea is that all teams go through the draft before free agent signings, and they can use the draft to obtain the exclusive right to sign a player. And the order that teams go in the draft is largely determined by the reverse standings from the previous season (so the worst team in the NBA from the previous season is guaranteed a very high spot in the draft, which means they can select a player they think will be very good). Obviously, there are ways to change draft order; there's a lottery now, so the worst team isn't guaranteed the top spot in the next draft, and teams can also choose to trade away their picks in upcoming drafts. But most spots don't change.

So if a team selects a player in the draft, they have the exclusive right to sign a contract with that player (I believe that right lasts for one year). And players almost always sign a contract with the team that drafts them - higher draft picks get bigger contracts, after all, as well as being able to play on a team where they probably won't be overshadowed by another player.