Registration is the alignment of image components that is required to correctly produce a clear, precise image. For example, the four colors in 4-color process printing must combine properly on the page to produce the desired result but the best example is when printing spot colors, the first color is run and then the second color and so forth.
Close registration occurs when the two colors are very close together. The printer often charges a close registration fee if the distance between the colors is outside an acceptable range which varies by printer. Some promotional products can only be printed in one color because either the process (pad, screen, offset) or the equipment can’t do multiple colors.