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

2. Lipids (Fats): These are important for energy storage, insulation, and cell membrane structure. They are composed of carbon, hydrogen, and oxygen, but in different ratios than carbohydrates. Examples include fats, oils, and waxes.

3. Proteins: These are the workhorses of the cell, performing a wide variety of functions including structural support, enzyme catalysis, and transport. They are composed of amino acids linked together in long chains.

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