The device primarily used to input text into a computer is a keyboard. Keyboards contain various keys, including letters, numbers, and symbols, allowing users to enter and modify text easily. In modern computing, they often come with additional features, such as programmable keys and multimedia controls, enhancing user interaction. While touchscreens may also provide text input capabilities, traditional keyboards remain the most common choice for tasks requiring substantial typing. They can be either mechanical or membrane types, depending on the technology used for key presses.