Hydrogen bonds are a type of weak chemical bond that occurs when a hydrogen atom covalently bonded to an electronegative atom, like oxygen or nitrogen, experiences an attraction to another electronegative atom. This interaction is crucial in many biological processes and contributes to the unique properties of water, such as its high surface tension and boiling point. These bonds are essential for the structure and function of DNA, as they help hold the two strands of the double helix together. Although weaker than covalent bonds, hydrogen bonds play a significant role in determining the shape and stability of molecules in living organisms.