For thousands of years, people have recognized the symptoms of infectious diseases, and every culture has found ways of healing the ill. In the 1600s, however, a revolutionary piece of equipment was invented—the microsope. By revealing the previously unseen world of microbes, the microscope opened the way to new approaches to understanding disease.

More powerful microscopes and new diagnostic techniques have since aided scientists conducting research at universities, medical facilities, and pharmaceutical research centers. The ability to see increasingly smaller microbes enables researchers to dissect those microbes in order to learn how they live and multiply, and even to analyze their genetic make—up.