**What is the CAP theorem?**

The CAP theorem is an idea that outlines various outcomes to show the limits of the average system. This theorem, also known as Brewer's theorem, essentially says that a distributed computer system cannot provide consistency, availability, and partition tolerance, all at the optimal level.

The CAP theorem is an idea that outlines various outcomes to show the limits of the average system. This theorem, also known as Brewer's theorem, essentially says that a distributed computer system cannot provide consistency, availability, and partition tolerance, all at the optimal level.

Many attribute the CAP theorem to the work of computer scientist Eric Brewer at the turn of the century. MIT scientists have published papers in support of this theory.

The CAP theorem is at the center of discussions about various models of data distribution in computer systems. Experts suggest that this resource-limited theory is part of what drives alternative methods of enforcing data consistency and other principles.

Part of the idea of the CAP theorem concerns the enforcement of two different data models. The first is atomicity, consistency, isolation and durability, or ACID. This set of properties enforces reliable data transactions. However, as some have pointed out, the idea of the CAP theorem has led to the popularity of models such as basically available soft-state services with eventual consistency - in this model, consistency is sacrificed for other priorities.

Another way to think about the CAP theorem is that it is in some ways similar to the old trading motto of availability for trading services - that slang adage claims that you can have services cheap, fast and of good quality, but not all three . This indicates the same kind of limited resources and results that the CAP theorem points to in computer science. The CAP theorem has also been used in analyzing new data analytics projects that use technologies like Hadoop to work with massive groups of organized and less organized data for corporate IT.

Another point about the CAP theorem has to do with the definition of 'availability'. Experts point out that you can have what is known as 'high availability' without all parts of the database being available at all times. This is one of several fixes to the idea of balancing consistency and availability in data transactions.