Flow cytometry is a technology that simultaneously counts and then examines multiple physical and/or chemical characteristics of single particles, usually cells, as they flow in a fluid stream through a beam of light. The properties measured include a particle’s relative size, relative granularity or internal complexity, and relative fluorescence intensity. These characteristics are determined using an optical-to-electronic coupling system that records how the cell scatters incident laser light and emits fluorescence. One of the most significant applications is immunophenotyping of cells - the most important tool in diagnosis and monitoring haematological disorders, such as acute and chronic leukemia, lymphoma, monoclonal gammopathy, myelodisplastic and myeloproliferative diseases.