checksum

Checksum is used for checking if the file is genuine or error free.It is done by comparingthe checksum generated from the file with the one provided by the source of that file. It is also referred as a hash sum and hash code.A checksum is a count of the number of bits in a transmission unit that is included with the unit so that the receiver can check to see whether the same number of bits arrived. Both TCP and UDP communication layers provide a checksum count and verification as one of their services.