Gram’s staining is an important microbiological staining technique which distinguishes bacteria into two types i.e. Gram Positive and Gram Negative depending upon the stain taken up by the cells. Gram positive bacteria take up the crystal violet stain and appear purple in colour while Gram negative bacteria take up safranin or basic fuchsin and appear red or pink in colour. Gram’s staining is also called as Differential staining. The bacteria take up different stains due to the difference in their physical and chemical composition of the cell wall. This is the basis of Gram’s staining.