a diamond
There are many kinds saw blade, diamond saw blade and carbide saw blade. You should choose the saw blade according to the application, like wood, metal, stone, concrete, wall and so on.
The set on the teeth makes the kerf (width of the cut) slightly wider then the blade so the saw can clear the dust from the cut and the blade won't bind up.
any saw is the opposite of the way the blade spins!
Unscrew the handle to relive the tension on the saw. Remove the old blade, hook the new blade over the pins on the saw and tighten the handle back up.
There is a great new glossary for circular saw blades here: http://www.toolstoday.com/t-saw-blades-glossary.aspx The Toolstoday Saw Blade Glossary defines the many different saw blade terms that you need to know when you purchase, or start working with saw blades.
Rip saw blades require a greater kerf to prevent the pinching of the blade by the stock.
Because it has a very narrow, flexible blade that makes curves easily
coated blade creates less friction/binding/heat. coated blade less likely to leave burn mark on wood due to blade overheating
There are many multi-tools on the market that do have a small saw blade on them.
a scroll saw is like a jig saw with a small straight blade while a skill saw is actually called a circular saw and typically has a 6 or 7 1/4 inch blade. it is sometimes called a skill saw because that is one of the brands that makes them.
Hack saw, coping saw.