Docker is an open-source platform that facilitates the creation, deployment, and management of containers. With Docker, developers can package an application along with all its dependencies into a container, ensuring that the software runs identically across different environments, whether in development, testing, or production. This technology has revolutionized software development by allowing for greater portability, scalability, and efficiency. Docker also integrates tools for versioning images, sharing containers in repositories like Docker Hub, and orchestrating automatic deployments. Its popularity is due to the fact that it simplifies complex processes and reduces environment conflicts, helping teams work collaboratively and accelerate the software life cycle.