Definition: A race condition happens when multiple operations access/change shared data concurrently and the final result depends on the order in which they execute.
The dangerous part is that each operation can look correct individually, while their combination produces an incorrect result.
Examples:
- Two customers buy the last product simultaneously.
- Two users receive the last available discount code.
- Two bank withdrawals happen simultaneously and both read the same account balance.
Typical solution: transactions, locks, atomic database operations, optimistic concurrency, etc.