What is the inner piece around a door frame called?

The inner piece around a door frame is referred to as the jamb. The jamb consists of the vertical components that support the door and form the sides of the door frame. It provides a structural element that holds the door in place and is essential for the door's proper operation and alignment. The jamb is also where the hinges are attached, allowing the door to swing open and closed.

In contrast, the header is the horizontal piece that spans the top of the door frame, providing additional support and stability. Trim, often decorative, is applied around the door frame to enhance its appearance but is not structural like the jamb. The sill, typically associated with windows, refers to the horizontal ledge at the bottom of the frame. Understanding the components of a door frame, including the jamb, is crucial for anyone in construction or looking to become a general contractor.