A yobibyte (YiB) is a unit of data storage equal to 280 bytes, or 1,208,925,819,614,629,174,706,176 bytes. It measures data at the same scale as a yottabyte, but has a binary prefix instead of a decimal prefix.
A yobibyte is slightly larger than a yottabyte (YB), which is 1024 bytes (1,000,000,000,000,000,000,000,000 bytes); a yobibyte is roughly 1.2089 yottabytes. A yobibyte is 1,024 zebibytes, and is currently the largest defined binary storage unit.
Due to historical naming conventions in the computer industry, which used decimal (base 10) prefixes for binary (base 2) measurements, the common definition of a measurement could mean different numbers. When computer engineers first began using the term kilobyte to refer to a binary measurement of 210 bytes (1,024 bytes), the difference between binary and decimal measurements was roughly 2%. As file sizes and storage capacities expanded, so did the difference between the two types of measurements — a yobibyte is more than 20% larger than a yottabyte. Using different terms to refer to binary and decimal measurements helps to address the confusion.
NOTE: For a list of other units of measurement, view this Help Center article.