Black and Blacker

Computer monitors are quite limited in their ability to show you how your job will be created on paper, particularly black. Ensuring all your black text is defined correctly will give you the sharp, clean text that you want.

In InDesign it is important to use the "Black" option from the swatches palette (shown below) or a CMYK custom colour where Cyan, Magenta and Yellow are all set to 0.

Using the wrong black can give a weak or fuzzy look to type, create halo effects around the edge of your type, and can mark the facing page. Registration prints solid in all colours and should not be used for any part of your design.
RGB colours do not translate well to CMYK colours, and RGB black translates to a combination of all 4 inks, though none are solid enough to give a nice black print.
Using 100% black will give you a clean black every time.

This simulation shows how each printed sheet may look under magnification using each variation of "black".