Hoechst 33342 is widely used in biological research for staining DNA in live and fixed cells. It is particularly valuable in fluorescence microscopy and flow cytometry due to its ability to bind to the minor groove of DNA and emit blue fluorescence under UV light. This makes it a key tool for studying cell cycle dynamics, nuclear morphology, and DNA content analysis. Additionally, it is used in cell viability assays and for identifying and sorting specific cell populations, such as stem cells, based on their DNA characteristics. Its permeability to live cells allows for real-time monitoring of cellular processes without causing significant toxicity.