If you wish to find a cure for AIDS or the common cold, then this is the major you should be considering. Microbiology belongs to the highly diversified field of biology and it deals with the study of small organisms such as yeast, protozoa, bacteria, and algae.
Microbiology majors study cell biology, environmental biology, pathogenic microbiology, biostatistics, cell physiology, and laboratory methods like microscopy. Students often focus heavily on the study of ecological interactions with human beings, unicellular organisms, and subcellular genetic matter.
Some schools will allow you to specialize in specific fields, which can alter or expand your employment opportunities after graduation. You could end up working in the food and beverage industry, agriculture field, or as a researcher. There's also the possibility that you may find employment in the pharmacology or biotech industries.