The sediment is the natural product of fermentation. Most people will wait until the beer is clear and "clean" looking before racking (siphoning) it off of the sediment into the bottling bucket. Then, more fermentable sugar is added to produce carbonation in the bottle. After that happens, there should be a tiny bit of sediment in the bottom of the bottle. It'll compact there, though, and when you refridgerate the bottles, it'll get pretty tightly packed. When you pour the bottle, you pour with one pour into a glass and leave the last 1/4 " or so behind, where the sediment remains. Then rinse that bottle right away, because dried yeast sediment hardens like concrete!