How to Create a Shell and Subshell on Rocky Linux 9.2

Shell is an environment in which we can run our commands, programs, and shell scripts. There are different flavors of a shell, just as there are different flavors of operating systems. Each flavor of shell has its own set of recognized commands and functions.
Subshell is a child shell that is spawned by the main shell (also known as the parent shell). It is a separate process with its own set of variables and command history, and allows you to execute commands and perform operations within a separate environment.