What is container? Container is an operating system level virtualization which allow to package applications and their dependencies and run them in a isolated environments. containers are branch of host operating system, and they share the host operating system's kernel and system libraries to complete their tasks. Container’s history In 1979 during the development of Unix V7 one new name chroot (change root) system call was introduced. it’s an Unix operating-system system call for changing the root directory of a process and it's children to a new location in the filesystem which is only visible to a given process. It was a beginning a process isolation: isolated disk space for each process or segregating file access for each process.