The researchers studied harmful algal blooms using satellite images to better understand their different types. They looked at over 100 images from around the world to identify six main types of red tides based on the colors they reflect. These types include blooms of cyanobacteria, green Noctiluca scintillans, red N. scintillans, Mesodinium rubrum, Lepidodinium chlorophorum, and various dinoflagellates. This study helps us recognize and monitor different harmful algal blooms more effectively.