A saw is a piece of toughened steel with teeth cut into one edge and a wooden or plastic handle. In some form or other, saws have been one of the principal woodcutting tools for thousands of years. The different types of saw for different jobs can roughly be divided into three main groups:

Saws differ in the size and shape of the blade, and the size, shape and number of teeth they have. Rip teeth, which are designed for cutting down the grain of wood, work like small chisels. The front edge of each tooth is more or less perpendicular to the saw edge and the back edge slopes at about 30 degrees. If saws with teeth like this are used to cut across wood grain, they tend to tear the fibres and leave a jagged edge. Rip teeth are generally straight-sharpened the tip of each tooth is perpendicular to the cutting line. Cross-cut teeth, which are designed for cutting across wood grain, generally slope back rather more and are usually cross-sharpened the teeth are sharpened at an angle to the saw so that the outside edge of each tooth is pointed. Cross-cut teeth tend to cut through the wood fibres rather like a knife. Fleam teeth slope back even more than cross-cut ones and have symmetrical points. They cut equally well on the push and pull strokes.

Saw teeth are usually set teeth are bent slightly outwards from the blade, alternately in each direction, so that the width of the slot cut by the saw is greater than the width of the blade. This prevents the saw jamming in the slot when cutting and lets you change the direction of the cut slightly during sawing. An even set is essential: badly set saws tend to wander.

For years, saw bladeshave been made from hardened steel which has been tempered to reduce the hardness (and increase the toughness) so that the blade wears well but is still soft enough to be sharpened with a file. More recently, however, saws have been introduced which have 'hardpoint' teeth the tips of the teeth are hardened to reduce wear. Saws with hard-point teeth can have several times the life of a conventional saw, but they cannot be sharpened by conventional methods and they are much more easily damaged when they meet a nail in their path.

There are, confusingly, two systems for describing the number of teeth a saw has - both are still based on imperial measurements. The first method records the number of complete teeth in an inch length of blade. The second method states the number of tooth points in an inch, starling on a point and including this in the count. The two methods can be confusing since a saw with eight points per inch actually has seven teeth per inch. The second method is the most widely used and the terminology is often shortened to talk about an eight-point saw, for example. Saws with large teeth generally cut faster but leave a rougher edge than saws with small teeth.

You might also want to learn how to cut metal with hacksaw blades and how to choose a good circular saw among many.