Metagenomics involves isolation, amplification, cloning and screening of DNA extracted from environmental samples. This direct approach that surmounts the need of cultivating microorganisms has opened up novel facets in biological research. In the absence of appropriate cultivation methods, more than 99% of microbial diversity awaits disclosure. Metagenomics transcends conventional genomics by a direct and comprehensive approach of analyzing a collective metagenome rather than individual genomes. Metagenomic analysis of human and insect gut, acid mine drainage, water bodies etc. have indicated possibility of finding novel organisms, bioactive molecules, pathways and has exposed the nature, role and dynamics of microbial communities in these niches.