Naming alkanes per standards listed in the IUPAC Gold Book is done according to the Klyne–Prelog system for specifying angles (called either torsional or dihedral angles) between substituents around a single bond:
* a torsion angle between 0° and ±90° is called syn  (s)
* a torsion angle between ±90° and 180° is called anti (a)
* a torsion angle between 30° and 150° or between −30° and −150° is called clinal (c)
* a torsion angle between 0° and ±30° or ±150° and 180° is called periplanar (p)
* a torsion angle between 0° and ±30° is called synperiplanar (sp), also called syn- or cis- conformation
* a torsion angle between 30° to 90° and −30° to −90° is called synclinal (sc), also called gauche or skew  
* a torsion angle between 90° and 150° or −90° and −150° is called anticlinal (ac)
* a torsion angle between ±150° and 180° is called antiperiplanar (ap), also called anti- or trans- conformation
Torsional strain or "Pitzer strain" refers to resistance to twisting about a bond.