Fasteners are a hardware device that mechanically joins or affixes two or more objects together. In general, they are used to create non-permanent joints; that is, joints that can be removed or dismantled without damaging the joining components. Welding is an example of creating permanent joints. There are three major steel types used in the industry: stainless steel, carbon steel, and alloy steel. The major grade used in stainless steel: 200 series, 300 series, and 400 series. Other alternative methods of joining materials include: crimping, welding, soldering, brazing, taping, gluing, cementing, or the use of other adhesives. The use of force may also be used, such as with magnets, vacuum (like suction cups), or even friction (like sticky pads). Some types of woodworking joints make use of separate internal reinforcements, such as dowels or biscuits, which in a sense can be considered fasteners within the scope of the joint system, although on their own they are not general purpose fasteners.