Hydrogen bonds are a type of weak chemical bond that occurs when a hydrogen atom, which is covalently bonded to a more electronegative atom like oxygen or nitrogen, experiences an attraction to another electronegative atom. This interaction is crucial in many biological processes, including the structure of DNA and the properties of water. These bonds are generally weaker than covalent bonds but play a significant role in determining the physical properties of substances. For example, the hydrogen bonds in water contribute to its high boiling point and surface tension, making it essential for life on Earth.