A Command Line Interface (CLI) is a text-based user interface that allows users to interact with a computer's operating system or software by typing commands. Unlike graphical user interfaces (GUIs), which use visual elements like buttons and icons, CLIs require users to input specific text commands to perform tasks, such as navigating files or running programs. CLIs are often favored by advanced users and developers for their speed and efficiency. They provide greater control over system functions and can automate repetitive tasks through scripting. Popular examples of CLIs include Bash on Linux and Command Prompt on Windows.