Two Phase Commit
In plain terms
A protocol ensuring all nodes commit a transaction or none do.
Going deeper
Two-phase commit coordinates a distributed transaction via a prepare phase then a commit phase, so all participants agree atomically. It guarantees all-or-nothing across nodes.
Under the hood
Blocking if the coordinator fails mid-protocol; strong consistency at the cost of availability and latency.
Examples
Distributed transactions, databases, atomic commits, coordinators, XA.
Think of it like...
Like everyone confirming 'ready?' before all signing a contract at once.