Lipids serve several vital roles in biological systems. They are key components of cell membranes, providing structural integrity and regulating what enters or leaves the cell. Additionally, lipids function as energy storage molecules, offering a dense energy source compared to carbohydrates. They also play important roles in signaling pathways as hormones and can act as precursors for vitamins. Certain lipids, like phospholipids, form lipid bilayers that are crucial for cell compartmentalization, allowing for specialized functions in different cellular regions. Overall, lipids are essential for maintaining life.