Docker is a free and open source OS-level virtualization system which allows us to pack and deliver applications together with their dependencies in isolated and reproducible environments called containers. Docker containers are built on the base of Images, which can become “dangling” in certain situations.
How to remove unnecessary files with BleachBit on Linux
BleachBit is a free and open source application available on Linux and Windows, which can be used, among the other things, to remove unnecessary files and directories from a filesystem. BleachBit can be used to free the caches of many applications, remove cookies and browsers history, but also to shred (secure delete) files and directories.