A yottabyte is the largest unit of measurement for computer data. It consists of 1,208,925,819,614,629,174,706,176 bytes (or 2 to the 80th power). It may also be estimated as 1,000,000,000,000,000,000,000,000 bytes (which is 10 to the 24th power).
Fortunately for those of us finite beings, yottabytes are not used very often. The prefix "Yotta" comes from "Iota," which is the ninth letter of the Greek alphabet. However, it seems more fitting that "yotta" refers to a "lotta" bytes.