The Apple Macintosh, released in 1984, was the first personal computer to use a GUI. Prior to this, users could only execute actions through a text-based command-line interface (CLI). A CLI required users to know and remember a lengthy list of specific commands.
For example, a CLI command might be “C:\Windows>”, which would execute the opening of a Windows folder on the screen. As you can imagine, navigating a computer using text commands was a tedious process. Thankfully, the GUI revolutionized computers by making them more intuitive and user-friendly. GUIs account for nearly all digital interfaces today.
GUIs are designed differently depending on the controlling input. A desktop computer is controlled using a pointer and keyboard shortcuts, but a tablet or mobile device is controlled by touch. GUI objects must be designed differently for pointer vs touchscreen. For example, a touchscreen requires larger icons (think of the apps on your phone) than a desktop, where you can access smaller icons using a pointer.
UI vs GUI
A user interface (UI) is the interaction between a user and a particular device. The user provides input and then sees the resulting output.
Therefore, graphical user interfaces and command-line interfaces are actually subsets of UI. They both include interacting with a device, but utilize different inputs.