Complexometric titrations involve reactions of ligands with suitable metal ions to generate metal–ligand complexes. The titration is often performed using a visual indicator, which first forms a relatively weak metal–indicator complex that gives the solution an initial color. As the titration approaches the equivalence point, all free metal ions are consumed, and any excess ligand displaces the indicator from the metal–indicator complex. The rapid color change that follows marks the end point of the titration.