Checking edge and face of a piece of lumber with combination square

You can use a combo square to measure out the squareness of your edge compared to the face.

Why are combination squares irreplaceable? Well, come on, I doubledog dare you to try to complete a woodworking project without one.

Checking miter cut with a combo square
A combo square will aid in checking the angles of your miter cuts to ensure they're exactly what you wanted.

I find it nearly impossible to even begin work in the shop without putting my hands on one of my combination squares.

Checking an end cut with your combo square
You can check the end cut with your square to ensure that it is perfectly flat after a cut.

From preparing stock to initial layout, all the way to squaring up subassemblies to mounting a project on a wall — combination squares are off the hook and in my hand.