Immutable Infrastructure is an approach where infrastructure components are replaced rather than changed. Instead of updating existing servers or components, new instances with the desired configuration are created and deployed, and the old ones are decommissioned. This ensures that the infrastructure is always in a known, consistent state and reduces the risk of configuration drift. Immutable infrastructure enhances reliability, simplifies rollback processes, and improves overall system stability. Tools like Docker and Kubernetes support immutable infrastructure by enabling the deployment of containerized applications in a consistent and repeatable manner.