Docker is a containerization tool that standardizes and simplifies application deployment. By encapsulating an application with all its dependencies within a container, Docker ensures that the application will run the same way regardless of the environment in which it is executed. This avoids compatibility issues and makes deployment faster and more reliable. Whether on a local server, in the cloud, or in a production environment, Docker guarantees consistency in application performance. It has become essential for developers and DevOps teams looking to enhance the efficiency and portability of their projects.