There are three informational files: Player Season Info, Player Career Info & Team Abbrevs. Each player was given a unique player ID to facilitate aggregation into career stats.

On the team side, there are 7 files:

totals & opponent totals
per game & opponent per game statistics
per 100 possessions & opponent per 100 possessions statistics (starting from 1974)
team summaries
On the player side, there are 10 files:

player totals
player per game stats
player per 36 minute stats
player per 100 possessions stats (starting from 1974)
player advanced stats
player play by play stats (starting from 1997) - percentage of time spent at different positions, fouls drawn & committed, etc
player shooting stats (starting from 1997) - success rate and attempt rate from different shot distances
end of season teams (All-Defense, All-Rookie, All-League)
end of season team voting (All-League)
all-star selections
awards voting results (Rookie of the Year, Sixth Man of the Year, Most Valuable Player, Defensive Player of the Year, Most Improved Player)

Data Obtained from Basketball Reference

Update 4/28:Dataset now includes complete team data for the 2023-2024

Update 5/3: Dataset now includes advanced player statistics for the 2023-2024 season.