Docker is a platform that allows developers to create, deploy, and manage applications in lightweight containers. These containers package an application and all its dependencies, ensuring that it runs consistently across different environments. This means that whether you're developing on your laptop or deploying to a server, the application behaves the same way. Using Docker simplifies the process of software development and deployment. It helps teams avoid the common "it works on my machine" problem by providing a standardized environment. With Docker, developers can easily share their applications and collaborate more effectively, speeding up the development cycle and improving overall productivity.