Antibonding orbitals are a type of molecular orbital that forms when atomic orbitals combine in a way that prevents bonding. They are created when two atomic orbitals overlap out of phase, leading to a region of higher energy. This means that electrons in antibonding orbitals can destabilize a molecule, making it less likely to form a stable bond. In contrast to bonding orbitals, which help hold atoms together, antibonding orbitals can be thought of as a barrier to bonding. For example, in a H2 molecule, the presence of an antibonding orbital can weaken the bond if it is occupied by electrons. Understanding these orbitals is crucial in chemistry for predicting molecular stability.