Containers provide an isolated, resource-controlled, and portable operating environment within an existing running operating system and that hosting OS can itself be either running on a single physical machine or on a single virtual machine (VM).

A container is an isolated place created by forming a virtual boundary using the process and namespace isolation technology by the host operating system so that an application running inside the container can run without affecting the rest of the system and without the system affecting the application. An app inside a container would feel like it is running inside a freshly installed OS (and the required prerequisites) on a computer.

The idea of such a virtual environment was first proposed in 1999 by an MIPT professor. It was an improvement on the chroot model and had three main components, which were:

• Groups of processes with namespace isolation
• Filesystem to share the code, and thus, save memory on disk and RAM
• Provide resource isolation as well as management