Which part of something is referred to as the 'interior'?

The term 'interior' refers specifically to the inner or internal part of something. In various contexts, such as architecture or design, the interior signifies what lies inside an object, structure, or space, distinguishing it from the outer layers or surfaces. This is critical in fields like hair cutting and styling, where understanding the structure of hair—root, shaft, and tip—can influence how styles are executed.

For instance, when cutting hair, knowledge of the interior structure is essential for creating volume, texture, and overall shape. This understanding allows a stylist to make informed decisions about layering and shaping techniques that can affect the hair's appearance and movement.