Why are lipids not all fats?

Lipids are a broad class of biomolecules that include not only fats but also oils, waxes, phospholipids, and steroids. While fats are a specific type of lipid primarily used for energy storage and insulation, other lipids serve different functions, such as forming cellular membranes (phospholipids) or acting as signaling molecules (steroids). Therefore, all fats are lipids, but not all lipids are fats, as they encompass a variety of structures and functions.