A sigma bond is a type of chemical bond that forms when two atomic orbitals overlap directly between the nuclei of two atoms. This overlap allows for the sharing of electrons, creating a strong bond that holds the atoms together. Sigma bonds are the first bonds formed between two atoms and can occur in single, double, or triple bonds, with each bond contributing to the overall stability of the molecule. In a molecule, sigma bonds are essential for defining its shape and structure. They are typically stronger than other types of bonds, such as pi bonds, which occur in double and triple bonds alongside sigma bonds. Understanding sigma bonds is crucial for studying molecular geometry and the behavior of compounds in chemistry.