Histology and cytology are the scientific term used to study the cellular and tissue architecture of plants and animals. Histology refers to the study of structure, composition, function of tissue system, whereas cytology refers to the study of structure, function and chemistry of the cell. In Cytology the cell is collected from the surface of lesion and is examined under the microscope. Both cytology and histology process are used during diagnostic procedure and research study. Histopathology is the also used to study the cell morphology and anatomy, in this process the cell is preserved, sliced and stained with the help of dye and is examined under the microscope. This type of test type is of high accuracy during diagnostic procedure, than cytology as cytology has less diagnostic accuracy and can be misleading during cancer diagnosis. With the help of cytology and histology, the diagnosis of various infectious and cell based diseases are examined such as cervical diseases, cancer, inflammatory diseases, autoimmune diseases, smallpox, and others. The advancement in the cytology and histology is also used during the research study, drug designing, and ligand-protein interaction, study of enzymes and numerousother medical conditions and methodologies.