Docker is an open-source platform for building, shipping, and running distributed applications. It works by creating a container for each application, isolating them from each other and the underlying host system.
For example, if you wanted to run a web server on your computer, you could use Docker to create a container for it. This container would contain all the necessary files and dependencies for running the web server, and would be isolated from the rest of the system, so that if the web server crashed, it wouldn’t affect the rest of your computer.