Docker is an open-source platform that automates the deployment, scaling, and management of applications using containers. On Debian 11, Docker can be easily installed and allows developers to create isolated environments for applications. It enables seamless execution across different systems, ensuring consistency between development, testing, and production environments. Docker provides tools to manage containers, images, and networks, making it ideal for microservices and cloud-native applications. With Docker, developers can streamline workflows and improve the scalability and efficiency of application deployment.