Bacterial cells in the natural environment and in infections are rarely found in a planktonic state. They are instead arranged in well-organized communities embedded in self-produced extracellular polymeric substances (EPS) called biofilms. The biofilm lifestyle confers a wide range of properties to the residing cells that allow efficient social interaction, permit nutrient availability, and ensure optimum usage of available enzymes and resources. The biofilm structure also permits a high level of tolerance to antimicrobials and host defense mechanisms. This creates a clinical milestone in treatment of biofilm-related infections. The medical consequences of biofilm formation and associated device-related infections (DRI) have been amplified with the widespread use of implanted medical devices. However, the biofilm structure itself represents a promising target in the development of novel antibacterial drugs. Therefore, this review represents an overview on the biofilm properties and the role of the EPS in the biofilm ecosystem. In addition, it emphasises the involvement of the biofilm structure as a therapeutic target in the development of novel antimicrobials and treatment of biofilm-related infections.