A partition tolerant distributed system should always keep operating, even when communication with one of its nodes cannot be established.

Brewer's theory can be applied to any distributed system in general. Since microservices architectures are based on the concepts of distributed computing, this means that this theory applies to them as well.

Even though the theory states that a system won't be able to accomplish all three properties at the same time, we should build systems that are able to handle failures gracefully. This is where the circuit breaker pattern can be applied.