Limnology as a process refers to the study of ponds, rivers, lakes, wetlands, streams, etc. Freshwater biology is a sub-division of limnology. It is the study of freshwater ecosystems, especially their scientific and biological aspects. It studies in detail the relationship of aquatic plants and animals with their ecosystem along with species distribution. This book is a compilation of chapters that discuss the most vital aspects in the field of freshwater biology. Such selected concepts that redefine this field have been presented in it. For all those who are interested in freshwater biology, this textbook can prove to be an essential guide.