The Kubernetes API is a set of programming interfaces that allows users to interact with a Kubernetes cluster. It provides a way to manage and control the various components of the cluster, such as pods, services, and deployments. By using the API, developers can automate tasks, retrieve information, and configure resources within the cluster. The API operates over HTTP and supports various operations like creating, updating, and deleting resources. It is designed to be extensible, allowing developers to add custom resources and controllers. This flexibility makes the Kubernetes API a powerful tool for managing containerized applications in a cloud-native environment.