A command-line is a text-based interface that allows users to interact with their computer's operating system by typing commands. Unlike graphical user interfaces (GUIs), where you click on icons and menus, the command-line requires you to input specific text commands to perform tasks. This can include anything from navigating files to running programs, making it a powerful tool for advanced users and developers. Using the command-line can seem intimidating at first, but it offers greater control and efficiency for many tasks. For example, developers often use the command-line to manage their code with tools like Git or to run scripts in programming languages like Python. With practice, users can become proficient and enjoy the speed and flexibility it provides.