Crystal/caramel malts contribute unfermentable sweetness. They don't need to be mashed, having been pre-mashed and caramelized in their manufacturing process. So you can throw them in with your mash if you brew AG or just steep them if you brew extract. They come in a variety of color ratings that also have different flavors.
Oh don't give me none more of that Old Janx Spirit
No, don't you give me none more of that Old Janx Spirit
For my head will fly, my tongue will lie, my eyes will fry and I may die
Won't you pour me one more of that sinful Old Janx Spirit