Walls serve several functions including enclosing spaces, providing privacy and security, and supporting floors and roofs. They are categorized as either load-bearing walls, which support structural loads, or non-load bearing walls, which only support their own weight. Different types of walls include external walls, internal walls, partition walls, party walls, separating walls, and curtain walls. Load-bearing walls can be constructed of solid masonry, have a cavity, or be faced or veneered.