CAP and ACID share a common vocabulary: Atomic, Consistent, and so on. But there is a catch: the words are the same but they mean totally different things. CAP comes from the distributed systems theory, while ACID belongs to database systems one.The Distributed Databases use both CAP and ACID vocabulary, so this obviously creates a lot of confusion. When someone says: “one should not give up consistency” what’s the consistency he is speaking about? Let’s have a look at the definitions of Atomic-Consistent-Isolated-Durable and Consistent-Available-Partition-tolerant.