Today in biotechnology large number of research is going on and most of them basically related with improving any variety of plant or animal by inserting a foreign gene with economically important characteristics but sometimes it can be improve by increase gene product or making product storage to a particular body part or product . All such things can be done only if we use a specific DNA sequence called promoter. In simple words promoter is as important as clutch during starting a bike along with kick. Promoter can be located near or within the coding region and help in initiating transcription, determining the level and place of gene where it is going to express. This book provide a vast knowledge of promoter under simple and short topics specially related to promoter role in transcription, promoter types and regulation of promoter by various factors along with evolutionary importance of promoter.