Double bond

 A type of covalent bond in which four electrons are shared between two atoms, as opposed to two electrons being shared between two atoms in a single bond. A different spatial arrangment of the pi and sigma electron orbitals makes the orbitals overlap  to create the double bond which gives a more rigid structure and prevents any rotation around the double bond. Double bonds are often found in alkenes and ring structures, where the double bond gives more stability due to resonance. They are more reactive than single bonds because they are more electron rich.