Diatoms are a large and diverse group of single-celled algae. Diatom-based indices are increasingly becoming important tools for assessment of environmental conditions in aquatic systems. Diatoms have long been lauded for their use as powerful and reliable environmental indicators. Diatoms are widely used as assessment tools in the understating / interpretation and management of environments. This guide has been compiled for those who wish to beginner of a study of the diatom taxa of India. It is hoped that this guide may also serve as a valuable aid-memoir for those diatomists involved in inferring a Beginner's guide to diatoms: collection, preparation and identification of diatom. In this manual is intended for those who wish to become familiar with the methods of collecting diatom samples in a meaningful and repeatable approach, whether the outputs from these samples will be used for taxonomy or biodiversity studies or to infer water quality. The application of diatom-based water quality monitoring has become a reality with the recent development of expertise in the fields of diatom taxonomy and ecology in India.