Microbes are major components on earth and make up 90% of the cells of the body.Distinctive microbial communities are found in different parts of the body.Host-associated microbial communities can be beneficial, harmless or destructive to the host.Oral microbial biofilms are multi-species communities where more than 700 bacterial species or phylotypes have been detected.The communities undergo dynamic changes with respect to structure and composition.Despite this complexity, formation of oral microbial biofilms is highly choreographed, beginning with initial colonization by a group of gram-positive aerobic bacteria, predominantly Streptococcus and Actinomyces, followed by a succession of gram-negative anaerobic bacteria.