Azure CLI (Command Line Interface) is a Tool to manage Azure resources. You can download it from following location.
Once installed you can open command prompt > type command az
Few common commands are following:
help to get list of commands
eg: az help
login to login to azure portal
eg: az login
group to operate on resource groups. (Sub command required)
eg: az group list
az interactive you can use this command to have Interactive Commands which will help with Auto-complete & Colored interfaces.
Under the Hood
Azure CLI uses Azure REST API for performing the actions.
Azure CLI is open source
Azure CLI is more readable compared with PowerShell