A bar clamp is a tool used in woodworking and metalworking to hold pieces of material together securely. It consists of a long metal or wooden bar with adjustable arms that can be tightened to apply pressure. This makes it ideal for tasks like gluing joints or assembling furniture, ensuring that the materials stay in place while the adhesive sets. Bar clamps come in various sizes and designs, allowing for versatility in different projects. They are often preferred over other types of clamps, such as C-clamps or spring clamps, due to their ability to apply even pressure across a wider area.