What is the difference between lined and unlined?

The difference between lined and unlined typically refers to the presence or absence of an internal layer or coating. Lined items, such as clothing or bags, have an additional layer of fabric or material on the inside, providing extra structure, warmth, or comfort. Unlined items lack this inner layer, making them lighter and often more breathable, but may also offer less protection or insulation. The choice between lined and unlined depends on the intended use and personal preference.