Dextrorotation and levorotation (also spelled as laevorotation) are terms to describe rotational direction of plane-polarized light as it approaches an observer. Dextrorotation is, like clockwise, right direction from top to bottom or also left direction from bottom to top; levorotation is opposite like counterclockwise is of observation from opposite direction. A compound with dextrorotation is called dextrorotatory or dextrorotary, while a compound with levorotation is called levorotatory or levorotary. Compounds with these properties are said to have optical activity and consist of chira...

An absolute configuration refers to the spatial arrangement of the atoms of a chiral molecular entity (or group) and its stereochemical description e.g. R or S, referring to Rectus, or Sinister, respectively. Absolute configurations for a chiral molecule (in pure form) are most often obtained by X-ray crystallography. All enantiomerically pure chiral molecules crystallise in one of the 65 Sohncke groups (chiral space groups). Alternative techniques are Optical rotatory dispersion, vibrational circular dichroism and the use of chiral shift reagents in proton NMR and Coulomb Explosion Imaging. When...