Cache coherence

Cache coherence is a way for computers to make sure that different pieces of memory are all using the same information. Imagine that you have two people sharing a secret. Both of them need to know the same secret, but if one person changes the secret and the other person doesn't know about it, they won't have the same information.

Cache coherence makes sure this doesn't happen. It's like a network between the different pieces of memory, so that if one piece of memory changes something, all the other pieces of memory will know about it right away. That way, they can all stay in sync with the same information.