The most basic reason that cells are stained is to enhance visualization of the cell or certain cellular components under a microscope. Cells may also be stained to highlight metabolic processes or to differentiate between live and dead cells in a sample.

What is the importance of a staining?

Staining is used to highlight important features of the tissue as well as to enhance the tissue contrast. Hematoxylin is a basic dye that is commonly used in this process and stains the nuclei giving it a bluish color while eosin (another stain dye used in histology) stains the cell's nucleus giving it a pinkish stain.

What is the importance of bacterial staining?

In bacterial culture specimens, it is often important to detect the presence of living bacterial cells. Staining methods such as fluorescent staining help to identify if culture cells are viable or not.