Aside from quality differences, carpet tile falls into two general categories: self-stick and dry-backed. The application of self-stick tiles is more or less self-explanatory. Installing dry-backed tiles (which are usually a little thicker) means laying down mastic or using doubled-faced carpet tape. Mastic applications usually leave a little more time to fine-tune the layout and keep the joints straight. Double-faced tape won't gum up the entire floor, a factor to consider if there's a chance you'll one day remove the tile from a solid wood floor. In either case, acclimate the tile to the room for 48 hours before you install it.