1. Carbohydrates: These are composed of carbon, hydrogen, and oxygen. They are the primary source of energy for living organisms and also play structural roles. Examples include sugars, starches, and cellulose.

2. Lipids (fats and oils): These are made up of carbon, hydrogen, and oxygen, but with a higher proportion of hydrogen than carbohydrates. They are important for energy storage, insulation, and cell membrane structure. Examples include triglycerides, phospholipids, and steroids.

3. Proteins: These are large, complex molecules made up of amino acids. They play a vast array of roles in the body, including structural support, enzyme catalysis, transport, and defense. Examples include enzymes, antibodies, and collagen.

4. Nucleic Acids: These are composed of nucleotides, which are made up of a sugar, a phosphate group, and a nitrogenous base. They are responsible for storing and transmitting genetic information. Examples include DNA and RNA.