Flow cytometry has revolutionized biomedical research by enabling rapid analysis and sorting of cells based on their physical and chemical properties. This review provides an overview of flow cytometry, its principles, and various applications. It illuminates how lasers and optics generate forward and side scatter signals, enabling size and granularity assessment. Fluorescence is central, using fluorophores to label specific cell populations. Moreover, the review explores the history of flow cytometry, highlighting milestones and contributors. It delves into the advancements in instrumentation, automation, and data analysis, resulting in improved accuracy, efficiency, and quality control. Different types of flow cytometry, including analytical, sorting, digital, imaging, and mass cytometry, are detailed, emphasizing their applications in cell analysis, diagnostics, and therapeutic development. The significance of fluorescence-activated cell sorting (FACS) in various fields is highlighted. Furthermore, the potential of AI and machine learning in data analysis is discussed. This comprehensive review showcases flow cytometry's transformative impact on diverse biomedical applications, emphasizing its potential for further innovation and discovery.