Learn More About Drill Bits and the Types
What are Drill Bits?
Drill bits are cutting tools that are made to fit into a rotating drill. A drill, fitted with a bit, is used to cut cylindrical holes of many different sizes in many different materials. The terms drill and drill bit can be confusing, as sometimes they are used to describe both the cutter holder (drill) and cutter (bit) itself.
There are a wide range of sizes and types of bits available. Steel ones are usually less expensive than carbide-tipped bits. Why buying a drill bit, shoppers should look for one that offers the quality and features most needed for the job.
Drill bits are often sold in sets along with a drill, and ones designed for home use may include general purpose bits for use mainly on wood. The three main types of wood bits are flat, dowel and auger. A flat bit is sharp with either a point or a screw in the middle to get through wood. A dowel bit may also be called a lip and spur bit.
Source: http://www.wisegeek.org/what-are-drill-bits.htm

Masonry Drill Bits
These can cut into many masonry surfaces. The shaft spirals up to a tip that is often composed of an extra-hardened material. Bit colors vary because of the different materials used. The tip may be a different color from the shaft due to a hardened coating. For instance, a chrome-vanadium shaft may be finished with a tungsten-carbide tip.
Diamond Drills
Using large machines is the preferred method of delineating mineralization. Diamond drills produce core which ranges from approximately one to two inches in diameter. Drill core is usually split in half by either a core splitter which produces samples of uneven size or by a diamond saw which produces halves of equal size. Half of the core is saved for geological examination and half is bagged and sent to the laboratory for analysis. Drill core is usually analyzed by assay methods.
Source: http://technology.infomine.com/articles/1/3458/drilling.equipment.bit/drill.bits.aspx
Paddle Bits
Paddle bits are flat, square-ended bits with a pointed tip jutting out the bottom. They resemble a paddle with a sharp point attached to the end of it. They are used to drill larger holes in wood, usually after a pilot hole has been drilled with a twist bit. Paddle bits generally range in size from about 1 inch up to 2 or 2 1/2 inches. Holes larger than that typically require a sturdier bit.
Source: http://www.doityourself.com/stry/different-sizes-of-drill-bits-explained
Spur Point Bit
Also known as a wood or dowel bit, they have a central point and two raised spurs that help keep the bit drilling straight. The bit cuts timber very fast when used in a power drill and leaves a clean sided hole. They are ideal for drilling holes for dowels as the sides of the holes are clean and parallel. Sizes range from 3 to 10mm. Spur point bits should only be used for drilling wood or some plastics.
Sharpening — a bit fiddly as it has to be done by hand. Sharpen the point and spurs with a fine file or edge of a fine grindstone; the angle between the point and spurs should be 90°.