The Release Readiness Checklist is a set of detailed steps used to ensure that a software release is ready and meets all requirements. It covers all the tasks necessary to deploy a successful and stable release, such as reviewing and testing the code, setting up the infrastructure, running a smoke test, and verifying the deployment. It includes tasks like verifying the environment, checking the system health, and verifying the security protocols and performance metrics. The checklist helps to ensure that all the components of the release are functioning properly before going live. It is an essential tool for successful software releases.