A phospholipid is a type of lipid molecule that is a key component of cell membranes. It consists of two fatty acid tails and a phosphate group attached to a glycerol backbone. The unique structure allows phospholipids to form a bilayer, where the hydrophilic (water-attracting) heads face outward towards the water, while the hydrophobic (water-repelling) tails face inward, away from the water. Phospholipids play a crucial role in maintaining the integrity and fluidity of cell membranes. They help regulate the movement of substances in and out of cells, contributing to essential processes such as communication and nutrient transport. Their amphipathic nature is vital for the formation of cellular structures in all living organisms, including plants and animals.