A bond angle is the angle formed between three atoms in a molecule, specifically between two bonds that share a common atom. It is an important aspect of molecular geometry, influencing the shape and reactivity of the molecule. Bond angles are typically measured in degrees and can vary depending on the type of atoms involved and their electron arrangements. In VSEPR (Valence Shell Electron Pair Repulsion) theory, bond angles help predict the spatial arrangement of atoms in a molecule. For example, in a water molecule, the bond angle between the two hydrogen atoms is approximately 104.5 degrees, which is influenced by the presence of lone pairs of electrons on the oxygen atom.