A CLI, or Command Line Interface, is a way for users to interact with a computer using text commands instead of graphical icons. Users type commands into a console or terminal window, and the computer executes these commands to perform tasks like file management, software installation, or system configuration. CLIs are often preferred by advanced users and developers because they can be faster and more efficient for certain tasks. They allow for automation through scripting and provide greater control over system operations compared to Graphical User Interfaces (GUIs), which rely on visual elements like buttons and menus.