Twist Drills are the most common type of drill bits. They have flutes that spiral around them that act as an archmedes screw to lift the shavings out of the hole. Twist drills can be used to cut metal, wood or plastic. Special carbide pieces in the points can be added to cut concrete. "Brad Point" bits should only be used on wood.
Spade Bits
Spade bits are used for rough boring in wood. They tend to cause splintering when they emerge from the workpiece so keep a scrap block behind it when possible or turn the wood over once the point emerges then drill from the other side. Always keep the point anchored in the wood. When putting a spade bit into a drill chuck keep it on the hex shape on the shank.
Forstner Bits
Forstner bits are used to drill large holes in wood. Their design allows them to cut flat bottomed holes with smooth sides. Clamp material being drilled securely.