Offsets track how far a consumer has read in each partition.
Offset storage:
- Stored in internal
__consumer_offsetstopic - Each consumer group has separate offsets
- Enables replay by resetting offset
Commit strategies:
- Auto-commit: Simple but risks data loss
- Manual sync: Blocks but ensures processing complete
- Manual async: Non-blocking but no immediate confirmation
Choose based on delivery guarantee requirements. At-least-once needs manual commit after processing.