You can drill holes in a many ways. Yet drilling with a drill bit is most known. Drilling bit comes in many sizes, materials, etc. Drilling usually is performed with a best cordless drill which cuts the material by drill bit rotation. Holes in wood, plastic and other soft materials can be made with any drill bit, but stainless steel, glass, and so on require specially designed drilling bits. Some drilling bits are difficult to use with handheld drills and require a drill press. Others are easy enough to use with hand or even hand-powered drills.
Conical point with a flat surface and linear chisel are used to improve cutting process, removing chips, and reducing thrust. In automated drilling machines are used multi-faceted drill points. Compared to usual bits, they require only a half of the thrust, and generate more then twice less heat.
Coatings help prevent rust, lessen friction and wear. Zirconium nitride coating adds the strength and improve precision drilling because it decreases friction significantly. Titanium coating is strong, adds corrosion resistance. Titanium also is heat-resistant and has an excellent fatigue limit.
The general purpose drill points are usually 118°. They are typically used for cutting into soft metals such as aluminum, whereas the 135° variant is best suited for hardened materials, such as stainless steel. A 135° bit is flatter, therefore more of its cutting lips start to perform the full metal cutting action.
You need longer bit to cut deeper hole, but they may wander or may have an inaccurate location due to their flexibility. Usually bits are available in a standard lengths: short length, most common Jobber-length, and long bits. Flutes are two or more spiral grooves that run the length of the drill body. They help to remove chips from the cutting edge, curl the chip for easier removal, allow the coolant and lubricant to get down to the cutting edge.
Any master working with a sheet metal, boxes or thin mild metal has a Step drill bit (Unibit). Unibits work fast and make relatively clean holes. Step drills come with just one single drill bit with progressively sized grooves and ridges. So you just need one tool for a variety of jobs. The one thing that you should avoid using step drill bits on is wood because they are known to split the wood.