Lag bolts are often referred to as lag screws. It looks like a screw rather than a bolt with its pointed end instead of the more common blunt end found on other bolts. It refers to a large wood screw with a head, square or hexagonal, driven by a wrench rather than a screwdriver. These screws may be made out of steel, stainless steel, silicon bronze, or hot-dipped galvanized to accommodate any project needs. It is mostly used in the construction field. Lag bolts are made from a variety of types and grades.

Lag screw is a like thick wood screws, but they have a square or hex head and use a wrench to turn them instead of a screwdriver. A lag screw subjects to both combined withdrawal and lateral loading may be cinsidered loaded primarily in withdrawl when the axis of the screw is at angle of 75 degree or more to the grain of the wood member holding the threaded portion of the screw. It is a heavy wood screw having a square bolt head. Lag screws are used to fasten relatively thin, often metal, cleats to wood structural elements. Lag screws are sometimes called lag bolts.