What Is Trapping?

In commercial printing trapping is the process of slightly overlapping colors to avoid gaps caused by registration errors. Color trapping compensates for registration errors  caused when printing plates are not aligned properly, and unwanted white gaps shows through between colors. Trapping prevents this by intentionally overlapping colors to eliminate any minute registration issues. In the past trapping was done by creating a slight distance between image emulsion in the film and the actual plate. Today most trapping done using automated software.