There are many shells, all of them do the same thing — they allow you to manipulate your filesystem.
I have like all shells excluding Powershell1.
The Bourne shell (sh)
Origins
The Stephen Bourne Shell first appeared in Version 7 Unix (1979) at Bell Labs. It replaced the earlier Thompson shell and became the standard shell for Unix systems in the late 1970s and 1980s. Its design introduced structured programming features (variables, control flow) to improve on the limitations of older shells.