In today's scenario there are lots of microrganisms showing their resistance to more and more synthetic drugs and in which the bacterial and fungal infections are among the most common infection affected to most of people and there is no any such drugs available which shows more efficacy to bacterial and fungal infections without side effects. This book, therefore provides a strong necessities of extracting essential oils from leaves of different plants and its active constituents (terpenoids) as crude drug find out by different chromatographic techniques i.e. TLC, HPLC and GC - MS helps to develop it in the form of alternative dosage form which will be helpful for exhibiting good antimicrobial activity towards most resistant bacterial and fungal infections along with lesser side effects.