Docker is a popular open-source platform that allows developers to easily create, deploy, and run applications in isolated containers. These containers provide a lightweight and portable environment for applications to run, making it easier to move them between different systems. Docker also helps to streamline the development process by allowing developers to package their code, dependencies, and configurations into a single container, eliminating the need for complex setup and configuration. This makes it a valuable tool for building and deploying applications in a fast, efficient, and consistent manner. With its growing popularity, Docker has become an essential tool for modern software development and deployment.