Restriction mapping is the process of obtaining structural information on a piece of DNA by the use of restriction enzymes. It is used to map an unknown segment of DNA by breaking it into pieces and identifying the locations of the breakpoints.
This method relies upon the use of proteins called restriction enzymes, which can cut, or digest, DNA molecules at short, specific sequences called restriction sites. After a DNA segment has been digested using a restriction enzyme, the resulting fragments can be examined using a laboratory method called gel electrophoresis. This is used to separate pieces of DNA according to their size.