Drill bits are cutting tools that create a round hole. Placed inside a drill, they spin at high speeds to bore the hole in whatever material you need a hole in. I know... pretty basic but it had to be said.

Twist Bits are for general purpose drilling. At a minimum, I buy Titanium drill bits that can be used in many different surfaces from soft wood to hard metal. You can get Cobalt bits as well which are supper hard bits. When cutting metal, you use a punch to create a dent for the twist bit. This "dent" acts as a drill-bit-guide for accuracy.

Brad-Point-Bits is a variation of a twist-bit used to cut holes in wood and has a center "brad" point that allows for accurate positioning and prevents skating. Brad-point bits are more expensive but the profile creates a much cleaner hole in most cases and the brad in the center makes it easy to place the bit accurately on layout lines.

Tapered W/ Counter Bore. I use this bit for pre-drilling holes with a counter bore at the top of the hole for screws. The tapered cut mimics the shape of the screw and allows for a stronger hold in the wood. The counter bore allows for the screws head to be flush with the works surface.

Carbide-Tip Masonry is another variation of the twist bit and it's used for cutting holes in concrete, brick and other masonry materials. This bit is typically used with a hammer-drill which both rotates and hammers the bit into the work piece. The hammering action of the drill breaks up the material at the front of the bit while the flutes of the bits body carry away the dust.

More Drill-Bit-Guides

Forstner Bits, named after their inventor, Benjamin Forstner, are great at boring precise flat bottom holes in wood. I've used them for making holes to inlay coins in plaques and other types of inlays. They can cut on the edge of a block of wood or overlapping holes. They're best used in a drill press since they require more force to push them into the wood, but you can use a hand drill (depending on the size of the bit). These bits also have a center point which guides it into the cut and leaves a small hole in the otherwise flat bottom.

Screw-Point Boring bit also known as an auger bit is used for boring larger holes for in wood. Electricians use them to create the large holes through framing to run electrical wires. The self-feeding screw point draws the bit into the wood and the large flutes remove the waste material as you drill.

Spade-bits are used for rough wood boring because they tend to splinter the wood when exiting the material.

Hole-Saws consist of a metal cylinder mounted on an arbor with pilot bit. These bits can have teeth for a cutting edge used to drill holes in wood, or industrial diamonds embedded for cutting hard material like faucet holes in a granite countertop. The one shown is for cutting wood and has a pilot bit. Diamond bits will not have a pilot bit. They are used with portable drills. They will come in several different sizes from 1/4 inch to over 5 inches. Industrial diamond embedded ones can be even larger.