Gram Staining

Gram staining (or the Gram's method) is an empirical method of differentiating bacterial species into two large groups (Gram-positive and Gram-negative) based on the chemical and physical properties of their cell walls.

Gram staining is one of the most useful staining procedures in bacteriological laboratory. The technique is widely used as a tool for differentiating Gram-negative and Gram-positive bacteria, as a first step to determine the identity of a particular bacterial sample.