Drill bits are cutting tools used to create cylindrical holes, almost always of circular cross-section. Bits are held in a tool called a drill, which rotates them and provides torque and axial force to create the hole. Specialized bits are also available for non-cylindrical-shaped holes.
A twist bit is the most common type of drill bit for home use. It works for general-purpose drilling in wood, plastic and light metal.
High-Speed Steel (HSS) drill bits can drill wood, fiberglass, PVC (polyvinyl chloride) and soft metals such as aluminum.
Cobalt drill bits are extremely hard and dissipate heat quickly. They're mostly used for boring in aluminum and tough metals such as stainless steel.
Black oxide-coated HSS drill bits have a finish designed to help resist corrosion and increase durability. They last longer than basic HSS bits and work well on a variety of materials, including metal, hardwood, softwood, PVC and fiberglass.
Titanium-coated HSS drill bits produce less friction. They're tougher than basic HSS bits and stay sharp longer. They work for drilling wood, metal, fiberglass and PVC.
Carbide-tipped drill bits stay sharp much longer than steel, HSS or titanium bits. They're effective for drilling tile and masonry.