By "damascus" I am assuming you are referring to pattern-welded steel (mechanical damascus). The idea is fairly simple: you take pieces of different steel (or the same steel in some cases) and forge-weld them together repeatedly, twisting and folding the billet in the process, which also produces a patterning on the surface when etched/polished.
In the past, the practice had a few uses, not the least of which was purifying the steel. Today, that issue is virtually nonexistent. The primary intention of pattern-welded steel is to be high quality while aesthetically pleasing. There are arguments made for the layers that intersect with the edge creating a microserration effect (allowing for a rather aggressive edge), but I don't know much about that and it is rarely the purpose of making the stuff.
There is no single type of pattern-welded steel. You can use virtually any combination of compatible steels, though there are a few favorites among various makers. When made and heat treated properly, a "damascus" blade should perform roughly as the equal of a monosteel version. For a "performance for the buck" person, it may not be the wisest choice, as it does not offer any serious advantages (and if poorly made, can be the inferior of single-steel blade).
Don't know how helpful that answer was, but I hope it helped a little.