Overview
Kafka is a distributed event streaming platform: it is built for high throughput, fault tolerance and durable storage of events. Unlike traditional messaging systems, events are not deleted after consumption; you define for how long Kafka retains them, using a per-topic setting. Each topic is split into partitions, ordered logs that events are appended to, and a consumer can rewind to an earlier offset and re-consume events that are still retained, which is what makes replay possible.
Analogy
Production tip
Check yourself
Why can a Kafka consumer replay data another consumer has already read?
Sources
- Introduction (4.2 documentation) (opens in a new tab)
- Design (4.2 documentation) (opens in a new tab)
- Powered By (Apache Kafka) (opens in a new tab)
Checked against Kafka 4.2 documentation on Oct 2026. Draft: not yet reviewed by a Kafka specialist. Releases move on, so confirm against the current documentation before you act on a number.