A peta is a prefix used with the metric system that stands for 1,000,000,000,000,000 (quadrillion), or 1015. A good example of where this prefix is used with computers is with a PB (petabyte).
What prefix is before a peta?
A tera is the prefix used before a peta.
What prefix is after a peta?
An exa is the prefix used after a peta.