Environment variables are a way to store information that can be used by programs and scripts.

They are key-value pairs that are stored in the system memory and are accessible by any process

Environment variables are often used in shell scripts to store important information like file paths, system settings, and user preferences

The env command is used to display the current environment variables set on the system.

We can also display the value of a specific environment variable: "echo $HOME"

To set a new environment variable: "export MY_VAR="Hello World"

It's important to note that environment variables are stored in the memory of the current shell session and are not persistent across reboots

To make an environment variable persistent, it must be set in a shell configuration file such as ~/.bashrc or ~/.profile.