The Bitrise Runner is a new capability that allows developers to use their own machine within their own infrastructure to run Bitrise builds, providing enhanced security, geolocation flexibility, and control over build environments. This introduces a paradigm shift in how build environments are managed compared to Bitrise-managed machines, with maintenance and setup effort involved but offering benefits such as faster builds, prewarming machines, and larger free disk space. The Runner is compatible with Linux and macOS platforms and offers a range of benefits including enhanced security, geolocation flexibility, in-house control, bare metal setup, and seamless transition to Bitrise for teams looking to scale their development processes.