Histochemistry is a branch of science that combines histology and chemistry to study the chemical composition of cells and tissues. It involves using specific staining techniques to visualize and identify various cellular components, such as proteins, carbohydrates, and lipids, under a microscope. This helps researchers understand the structure and function of different tissues in both healthy and diseased states. By applying chemical reactions to tissue samples, histochemists can detect the presence and distribution of biomolecules. This information is crucial for diagnosing diseases, studying developmental processes, and researching the effects of drugs on tissues. Overall, histochemistry plays a vital role in both basic and applied biological sciences.