CAPteoreemist

The CAP theorem, also known as Brewer's theorem, is a fundamental concept in distributed computer systems. It states that it is impossible for a distributed data store to simultaneously provide more than two out of the following three guarantees: Consistency, Availability, and Partition Tolerance.

Consistency in this context means that every read receives the most recent write or an error. Availability means that every request receives a response, without a guarantee that it contains the most recent write. Partition tolerance means that the system continues to operate despite an arbitrary number of messages being dropped (or delayed) by the network between nodes.

Since network partitions are a reality in distributed systems, the CAP theorem essentially forces a trade-off between Consistency and Availability. A system can choose to be CP, meaning it will sacrifice availability during a network partition to ensure consistency. Alternatively, it can be AP, prioritizing availability even if it means returning stale data during a partition. It is generally impossible to achieve CA in a distributed system because network partitions are inevitable. Therefore, most distributed systems must make a choice between C and A when a partition occurs. The choice of which two guarantees to prioritize depends heavily on the specific requirements and use case of the distributed system.