CentOS Stream is a rolling-release Linux distribution that sits between Fedora, a bleeding-edge community project, and Red Hat Enterprise Linux (RHEL), the stable enterprise-ready platform. It’s essentially the testing ground for the next version of RHEL.
While Fedora is often too cutting-edge for some use cases and RHEL focuses on long-term stability, CentOS Stream provides a middle ground, which allows developers to contribute, test, and preview features that will eventually make their way into RHEL.