If you are out walking in the woods, a trap is something you accidentally put your foot into, resulting in considerable pain and a substantial delay to your journey. In printing, “trapping” refers to something very different—but if it is ignored or forgotten, it can also cause substantial delays while the job is reprinted, and the pain of increased costs as a result.

Trapping actually means allowing one color to very slightly overprint another where the edges of the two touch. As registration between the plates on a printing press is never quite perfect, a lack of trapping will probably result in a slight gap between the colors at some point. As the gap was not part of the original design, and as it will probably stand out like a sore thumb, it is a problem. Fortunately, it a problem that is easily fixed, as long as you know what to do.

Automatic trapping specifications have been built into most good graphics software, and in some cases you can manually specify a trap if you think the automatic feature will not be enough. While these are both very helpful, most helpful of all is to know how each method functions.