This article focuses on chemical forms of communication that occur within and between species of bacteria. In their natural environments, bacteria predominantly exist in multi-cellular and even multi-species communities. Bacteria gain advantages from coordinating physiological functions across populations. The orchestration of population-based processes, such as biofilm formation or motility, require communication. In addition, communities may be collections of different species, which organize and interact by mechanisms that are poorly understood. Specialized forms of communication, which include the production of antibiotics and other bioactive metabolites, provide fitness advantages in competitive multi-species communities. Whether in communication, competition, or even cooperation between species, specialized metabolism is the wellspring for natural products produced by bacteria. This article highlights many forms of chemical communication used by bacteria, insights from the literature into the connections between communication and natural products, and studies that suggest new avenues for understanding the mechanisms of communication.