A byte is a set of 8 bits that represent a single character in the computer's memory. Do not confuse this term with "bite," as in taking a bite of a cookie, because that is totally different. While bits are often used to measure data transfer speeds, bytes are used to measure file sizes, hard disk space, and computer memory. Larger amounts of data are measured in units such as megabytes, gigabytes, and terabytes. For example, one kilobyte is equal to 1,024 bytes.
For a list of all the different units of measurements, view this Help Center article.