4 main uses jump to mind immediately.

• Covers the rough joint between plaster and floor.

• Covers the edge of the floor, hiding poor cuts, and allowing space for expansion or shifting without bowing (more important for wood floors).

• Protects the bottom of the wall from impact damage. Shoes, furniture, vacuum cleaners or water from mopping all damage plaster. The skirting board acts as a kick shield. Wood holds up far better, and gloss paint is waterproof.

• Appearance - when you don't have a skirting board, the walls can look particularly bland. It sounds trite, but it's definitely noticeable.