Terraform is a tool for provisioning infrastructure(or managing Infrastructure as Code). It supports multiple providers(eg, AWS, Google Cloud, Azure, OpenStack..)
As per official website
Git is a free and open source distributed version control system designed to handle everything from small to very large projects with speed and efficiency.
Before going into the in-depth of Shell Scripting, the first question we need to ask what is a Shell?
Shell is a command interpreter.
A Shell script is nothing but a list of commands stored in a file.