# Update Client Update Client is a reusable updater core that speaks the [Omaha 3.1 protocol](../../docs/updater/protocol_3_1.md). It powers the component and extension updaters, as well as the out-of-process updater in [chrome/updater](../../chrome/updater/README.md). The entry point to the library is `update_client.h`, and the comments in that file describe the library.