Cells are difficult to see in light microscopy,so to help visualize the structure of cell ,dyes are used to impart a particular color to cells.
Eukaryotic cells have both acidic and basic components so,
Hematoxylin and Eosin staining is the standard method of staining used for an eukaryotic cell.
Hematoxylin is a basic dye that binds to negatively charged DNA and RNA and is blue in colour.Eosin is pink in color and it binds to positively charged particles like the mitochondria and other components of cytoplasm.