From Learn Linux in a Month of Lunches by Steven Ovadia
Linux software installation, removal, and updating is handled by package managers. A package manager is what operates between us, the users, and the distribution software repositories. It’s where you look for software to install. The package manager is also what keeps software up-to-date on your computer.
By Jeff Nickoloff, author of Docker in Action
Volumes are ways to declare shared state or stateful data with a life cycle independent of a running program. Since containers are segregated in all other ways, volumes provide a mechanism to specify a scope of interaction through file access. In this article, I talk about volumes and their benefits.