Today, there are two primary forms of carpet installation: tackless installation and direct glue down. Tackless installation occurs when tack strip is installed around the perimeter of a room and the carpet is stretched over padding onto those tack strips to hold it in place. Before this installation method, carpet was tacked down with staples throughout the installation which is why the new method is called "tackless" installation; as you no longer need nails in the middle of the floor. Direct glue down occurs when you spread special carpet adhesive over the substrate and then roll the carpet onto the glue to hold it in place.