Flow cytometry is a technique used to analyze and quantify various cellular characteristics in a sample. It involves passing cells through a laser beam and measuring the fluorescent light emitted by the cells. This allows researchers to examine properties such as cell size, shape, and DNA content, as well as identify different cell types based on specific surface markers. Flow cytometry is commonly used in research and clinical settings for a wide range of applications, including immunology, cancer research, and stem cell analysis. By providing detailed information about individual cells within a population, flow cytometry can help scientists better understand complex biological processes and diseases.