Distributed Systems

Understanding the CAP Theorem

A practical look at consistency, availability, and partition tolerance — and why you can only pick two during a network partition.

January 10, 2026
#cap-theorem#consistency#availability#partition-tolerance

The CAP theorem states that a distributed data store can guarantee at most two of three properties simultaneously: Consistency (every read returns the most recent write), Availability (every request gets a non-error response), and Partition Tolerance (the system continues operating despite network partitions). Because partitions are unavoidable in real networks, the practical choice is always between consistency and availability.

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