What is an offset in Kafka?

An offset is a unique, monotonically increasing integer that identifies a message within a specific partition. Offsets start at 0 and increment by 1 for every new message appended to a partition. Offsets are unique per-partition, not per-topic — the same offset number can exist in each partition. Consumers use offsets to track which messages they've processed. Committing an offset means the consumer acknowledges it has processed all messages up to that offset.

Expected key concepts: unique, monotonically increasing, integer, per-partition, track, processed, commit, acknowledge