Using Your Range Names in Formulas
The great thing about using range names in your formulas is that they automatically document their function. This is especially helpful to coworkers who have to use your spreadsheets but who had no part in their design. When using names in your formulas, you can assign the names as you construct new formulas in the worksheet, or you can add them after the fact to existing formulas.
Following these sections:
Using range names in new formulas and Assigning range names to existing formulas