A scanner is a device specifically designed to capture images or documents and convert them into digital data that can be used, stored, or manipulated on a computer. Scanners are often used in offices and homes to digitize documents, photos, and other paper-based content. A printer is used to create hard copies of digital documents, a keyboard is for inputting data into the computer, and an external hard drive is a storage device used to store data outside of a computer's internal storage.