What is after peta byte?

A petabyte is either 1 000 000 000 000 000 bytes
or 1024 x 1024 x 1024 x 1024 x 1024 bytes.

It is the next in the series kilobyte, megabyte, gigabyte, terabyte, petabyte, ...

peta means 1015 but in computing 1000 and 1024 sometimes get interchanged.