All over the world's waters, numerous small organisms from various groups of the plant and animal kingdoms thrive. More than 1500 species are described in detail in this book. The presented plant and animal groups can be quickly found thanks to a type key. Detailed illustrations make it easy to identify the species. The various microorganisms are showcased in numerous illustrations. Additionally, there is information on microphotography with digital cameras and biological water analysis. Practical tips and current sources for microscopy complete this standard work for microscopists and limnologists.