Brewer's theorem

Brewer's theorem states that in distributed computing systems, it's impossible to achieve all three of the following at the same time: consistency (all nodes see the same data), availability (the system remains operational and responds to requests), and partition tolerance (the system continues to function despite network failures). You can only have two at once. For example, you might choose consistency and partition tolerance, accepting some downtime during network issues, or availability and partition tolerance, allowing different nodes to show different data temporarily. This helps system designers make informed trade-offs based on their priorities.