The combination square is adjustable, consisting of a rigid steel rule, typically 12 inches long, with a headpiece that slides along its length. The headpiece has both a 90-degree edge and one that forms a 45-degree angle with respect to the rule. It’s ideal for marking (and checking) both 90-degree crosscuts and miter cuts. A bubble level in its handle makes the tool useful for leveling as well.

Related: Tool Tip—Toolboxes

The sealed vials of the torpedo level contain water, alcohol, or another clear liquid and an all-important air bubble. Each tube or vial is slightly curved and has two parallel lines drawn at its center. When the bubble is aligned between the hairlines, it indicates that the object being trued is perfectly vertical or horizontal, depending on the orientation of the vials and how the level has been placed on the object.

Related: Quick Tip—Using a Level

The basic handsaw has a blade roughly two feet long that tapers from the heel (at the handle) to its toe. The most common use is simple cutoff work when it’s quicker to grab a handsaw than a power saw. The teeth may be designed for cutting across the grain (crosscut saws) or for cutting with it (ripsaws). A 10- or 12-tooth crosscut saw of 22 inches is a good basic saw that can also rip a board if necessary.

Related: Handling Your Handsaw

The basic electric drill consists of a motor built into a pistol-shaped body. Instead of a gun barrel, though, there’s a gripping device called a chuck into which one of a wide variety of  drill bits are inserted. Older models lock the bits in place using a key that tightens the chuck, but most new drills use a keyless chuck that requires only the grip of your hand to tighten it.

When working with wood in particular, a clamp is essential for pulling together pieces that need to be glued and for holding them tight and flush until the glue sets. For most around-the-house jobs, C-clamps or bar clamps will do the trick. C-clamps have jaws in the shape of the letter C. Bar clamps are usually larger, with a fixed jaw at one end and another on a tail slide that moves up and down the bar's length.

Related: Clamps

A convenient, one-handed tool, the random orbital sander is driven by an electric motor. The motor spins a shaft on which a counterweight is mounted, causing the sander to spin and wiggle, never the same way twice. The tool does a neat job, producing little or no scratching across the grain. Using prefabricated sandpaper disks, available from coarse to fine, it can remove lots of material quickly or produce a fine finish.

Related: Finishing Sanders

The staple gun can be used to fasten all kinds of materials in home construction and maintenance work. Roofing contractors, insulation installers, and carpenters as well as homeowners and hobbyists find a multitude of uses for staplers every day. Staple guns come in hand-powered and electric models, although the most common variety is powered by a spring.

These adjustable pliers are useful as a hand-held vice or clamp. They lock firmly onto a workpiece, usually one of metal. They are also known as plier wrenches, lever-wrench pliers, and by the proprietary name Vise-Grips. Locking pliers are sold in several designs (with long-nose, flat, and even C-clamp jaws), but the standard design has serrated, straight jaws.

Related: Pliers

Though the bevel gauge is a near relation of the square, its purpose is to help fabricate pieces that are not square. The tool consists of a handle (or stock) with an attached tongue (or blade). The tongue fits into a groove cut into the head of the stock, where it’s fastened with a locking mechanism. To match an existing angle, place the stock on your workpiece, set the gauge to the appropriate angle, then simply move the bevel gauge onto the stock from which you’ll be making the companion piece.

Related: Bevel Gauges

The carpenter’s square is actually an L-shaped tool, usually with a 2-inch-wide, 24-inch-long leg perpendicular to a 1-1/2-inch-wide, 16-inch-long tongue. The most common use is for framing, laying out and marking patterns for framing, roofing, and stairway work. It’s also useful as a straightedge for determining the flatness of a surface, and for marking cutoff work on wide stock.

Related: How to Determine If Your Carpenter's Square Is True

You don’t need a graduate degree in physics to understand that a string suspended with a weight at the bottom will be both precisely vertical, or "plumb," AND perpendicular to any level plane through which it passes. The plumb bob, obviously, is the companion tool to the level. Well-machined and well-balanced bobs have pointed tips that make them more precise to use.

Related: The Plumb Bob

With the possible exception of the electric drill, the Skilsaw, or circular handsaw, is the power tool most often found in the average homeowner’s tool chest. It’s easy to use, affordable, and astonishingly flexible and practical. It’s designed to cut boards to size, typically using a 7-1/4-inch-diameter blade. It’s a powerful and efficient tool, but one that requires safety precautions.

Related: How To Cut Straight Lines with a Circular Saw

If you are interested in more about tools, consider:

Get a Grip: 8 Clamps to Help You Handle Any Project

Top 5 Tool-Buying Tips

7 Essential Woodworking Tools