The prefix "Peta-" is a unit of measurement in the International System of Units (SI) that denotes a factor of 10^15, or one quadrillion. It is commonly used in fields such as computing and data storage, where large quantities are often measured. For example, a petabyte (PB) equals 1,024 terabytes (TB) and is used to describe massive data sets. In addition to computing, "Peta-" can also refer to other scientific measurements, such as petameters (Pm), which are used to measure distances in astronomy. This prefix helps simplify the expression of very large numbers, making it easier to communicate and understand vast quantities in various disciplines.