A reinforcing bar, also known as "square steel" or "square-shaped steel," is a type of steel that has a square shape in both dimensions, characterized by equal-length sides and 90-degree angles. Reinforcing bar is typically made from carbon steel or other steel alloys and comes in various sizes to suit specific applications.

The applications of reinforcing bars include:

1. Construction: The reinforcing bar is commonly used in construction projects to create load-bearing structures. It can be used in constructing columns, beams, building frames, and other structural components.

2. Machinery Fabrication: A reinforcing bar is also used in the machinery fabrication industry to produce machine parts, machine frames, or any component that requires high load-bearing capacity and strength.

3. Decor and Interior: In interior design and decor, reinforcing bars can create decorative products such as tables, chairs, shelves, and other internal components.

4. Mechanical and Product Design: A reinforcing bar is often used in mechanical and product design to create mechanical components or parts in products, such as partitions, edges between metal sheets, and various other applications.

5. Elevator and Staircase Construction: A reinforcing bar can be used to construct elevators, staircases, and other lifting systems in buildings and public infrastructure.

Reinforcing bar is favored in applications that require load-bearing capacity, high strength, and mechanical stability. It can be easily cut, bent, welded, and machined for various purposes.