QuickPar is a utility for creating Parity Volumes using the Reed Solomon algorithm. For details of the algorithm used, see the parchive website at SourceForge.
Parity Volumes may be used to verify that a set of files have not been corrupted, or to reconstruct damaged files (providing that you have a sufficient quantity of Parity Volumes to match the missing or damaged files).
QuickPar uses the PAR version 2.0 specification. You can read about the differences between PAR version 1.0 and PAR version 2.0 here.