Definition
A CLI (Command-Line Interface) is a text-based way of interacting with a computer or software application. Instead of clicking buttons in a visual interface, you type commands and the system responds with text output. Developers use CLIs to run code, manage servers, install software, execute database operations, and automate repetitive tasks. The terminal or command prompt on your computer is a CLI.
Why It Matters
CLIs appear constantly in development workflows. When your developer says they “ran a migration” or “deployed via the command line,” they used a CLI. While you will rarely interact with one directly, understanding what a CLI is helps you follow technical conversations, read project documentation, and make sense of deployment processes. It also explains why developers often prefer text commands over graphical interfaces — CLIs are faster for repetitive tasks, easier to automate, and more precise when managing servers or running complex operations.
Example
Your development team needs to update the database structure on your live server. Instead of clicking through a database management tool and manually adding columns, they run a single command through the CLI: a migration command that applies the pre-written changes, verifies they succeeded, and logs the result. The entire process takes seconds and can be repeated identically on any environment — development, staging, or production.