Which tool can be used for both measuring and marking wood?

The square is an essential tool in carpentry that serves both as a measuring and marking tool. Its primary function is to ensure that angles are square, typically at 90 degrees, which is crucial for creating straight cuts and ensuring structural integrity in woodworking. The square can be used to measure distances along the edges of wood and also provides a straight edge to mark lines for cutting or drilling.

While a tape measure is primarily for measuring lengths and a caliper is excellent for precise measurements, they do not fulfill the marking function as the square does. A protractor is specifically designed for measuring angles but may not provide the straight edge necessary for marking. Thus, the versatility of the square for both measuring dimensions and marking cutting lines makes it the correct choice for this question.