Antibiotic sensitivity testing, is a test which uses antibiotic impregnated wafers to test whether bacteria are affected by antibiotics. In this test, wafers containing antibiotics are placed on an agar plate where bacteria have been place, and the plate is let to incubate. If an antibiotic stops the bacteria from growing or kills the bacteria, there will be an area around the wafer where the bacteria have not grown enough to be visible. This is the zone of inhibition.
Disk diffusion test