This document summarizes oral microbial flora and bacterial morphology. It discusses the difference between prokaryotic and eukaryotic cells and describes bacterial size, shape, anatomy including cell wall, cytoplasm membrane, nucleus, capsule and flagella. The document also covers bacterial growth, staining techniques, normal oral flora and the most predominant bacterial taxa found in the oral cavity. It explains how the oral cavity acquires bacteria initially and how the flora varies with age and eruption of teeth.