The document discusses bond rotation in organic molecules. It explains that single bonds between sp3 hybridized carbon atoms can freely rotate, resulting in different conformers of the molecule depending on the orientation of the groups. Double and triple bonds are more rigid and cannot rotate as much as this would disrupt the pi bonding. This restriction of rotation around multiple bonds can lead to the existence of isomers that have the same molecular formula but different spatial arrangements, known as stereoisomers.