Bacteria are single-celled microorganisms with no nuclear membrane, metabolic activity, and binary fission division. In terms of medicine, they are a major source of disease. Bacteria appear to be simple forms of life on the surface, but they are smart and adaptive organisms. Bacteriology is a branch of science. It's a subfield of microbiology that studies bacteria. The majority of diseases with a bacteriologic aetiology have been known for hundreds of years. Medical researchers have been focusing on pathogenic processes and host defences in recent years. Understanding the underlying properties of the bacteria, the host, and their interactions is required to comprehend host-parasite connections involving specific infections.