Hydrogen bonding is a type of attractive interaction that occurs between a hydrogen atom covalently bonded to a highly electronegative atom, such as oxygen, nitrogen, or fluorine, and another electronegative atom. This bond is weaker than covalent bonds but stronger than van der Waals forces, playing a crucial role in the properties of water and biological molecules like DNA and proteins. These bonds are essential for maintaining the structure and stability of many substances. For example, in water, hydrogen bonds contribute to its high boiling point and surface tension. In DNA, hydrogen bonds between base pairs help hold the double helix structure together.