If you are building or using a distributed database where multiple nodes can accept writes on the same entities, you should know a bit about CRDTs…
In traditional distributed databases, when you write, the system must confirm with other nodes to maintain consistency (quorums). This means you need network connectivity and consensus.
CRDTs (conflict-free replicated data types) flip this model. Each node can accept writes independently without coordination. Eventually, all nodes would independently converge to the same state without the need for their coordination at write time.
This comes in handy when building an application that lets you write to your local copy while completely offline. When nodes eventually reconnect, the CRDT merge algorithm automatically reconciles all changes deterministically.
This “write locally, sync later” property also makes CRDTs super useful for local-first applications. Your notes, todos, contacts, calendar, and chat messages can all sync in the background whenever your devices are online.
The only catch here is the constraint that CRDTs do not work well for high-volume writes from many nodes.
Still, CRDTs are pretty handy to build use cases that need to work seamlessly offline and reduce dependence on centralized servers.