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

2. Lipids (fats and oils): These are composed of carbon, hydrogen, and oxygen, but with a higher proportion of hydrogen than carbohydrates. They are important for energy storage, insulation, and forming cell membranes. Examples include fats, oils, and waxes.

3. Proteins: These are composed of carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur. They are essential for a wide range of biological functions, including enzymes, hormones, antibodies, and structural components of cells and tissues. Examples include enzymes, collagen, and hemoglobin.

4. Nucleic acids: These are composed of carbon, hydrogen, oxygen, nitrogen, and phosphorus. They are responsible for storing and transmitting genetic information. Examples include DNA and RNA.