Each build in TeamCity is assigned a build number, which is a string identifier composed according to the pattern specified in the build configuration setting on the Configuring General Settings page.This number is displayed in the UI and passed into the build as a Predefined Build Parameter.
A build number can be:
- Used to download artifacts
- Referenced as a property
- Shared for builds connected by a dependency
- Used in artifact dependencies
- Set with help of service messages
Administrator's Guide: Configuring General Settings