Lipids dissolve in non-polar solvents such as chloroform, benzene and diethyl ether. They do not dissolve in polar solvents such as water. The only exceptions to this rule are the phospholipids, which will partially dissolve in water.
Phospholipids are partially soluble in polar solutions such as water because of the phosphate group at the molecule's head. This phosphate group is polar, and that portion will dissolve in water while the non-polar tail remains insoluble. Phospholipids' partial solubility is integral to their function as cell membranes.
The most common lipids found in nature are the triglycerides. Animal fats and vegetable oils are primarily composed of triglycerides, which may be either saturated or unsaturated. Saturated fats are solid at room temperature and occur most often in animal fat. Unsaturated fats are more common in vegetable oils and are liquid at room temperature.
Steroids are the third type of lipid. Steroids are ring-shaped lipids used in cell membranes and as hormones within the body. Cholesterol is the most common steroid hormone; other common steroid hormones found in humans are estrogen, testosterone, progesterone, cortisol and bile salts. Steroids do not share many physical or chemical properties with other lipids. Their insolubility in water is their primary similarity.