Biofilms form when microbes grow attached to a surface and become encased in a self-produced extracellular matrix. The fact that biofilm growth has been observed in most bacteria studied to date suggests that this form of growth is important in the ecology and physiology of most, if not all, bacteria. Biofilms have profound impact on human health, since they can form on the surfaces of indwelling medical devices and are inherently more resistant to most antimicrobial agents, making them extremely difficult to eradicate. In this talk, I will present the biological aspects of biofilm formation using Bacillus subtilis as a model system. Furthermore, I will discuss how this understanding is helping in the search for compounds that inhibit biofilm development.