Diols are organic compounds that contain two hydroxyl (-OH) groups attached to different carbon atoms. They are also known as glycols and can be classified into two main types: 1,2-diol (where the hydroxyl groups are on adjacent carbons) and 1,3-diol (where they are separated by one carbon). Diols are commonly used in the production of plastics, antifreeze, and as solvents. These compounds can be found in various natural and synthetic substances. For example, ethylene glycol is a widely used diol in antifreeze formulations, while glycerol is a natural diol found in fats and oils. Diols play a significant role in chemical reactions, such as esterification, and are important in the synthesis of various materials.