Immunohistochemistry is a technique used in biology and medicine to visualize proteins within tissue sections. It involves the use of antibodies, which are molecules that can recognize and bind to specific proteins or other cellular components, to tag or stain the protein of interest within a sample. This allows researchers to study the distribution and localization of specific proteins in cells and tissues, providing valuable information about their function and role in various biological processes. Immunohistochemistry is commonly used in diagnostic pathology to identify cancerous or precancerous cells based on the presence of certain proteins, as well as in research settings to study gene expression and protein localization in tissues.