Bacteria are microscopic, single-celled organisms that perform a wide variety of functions.
(More detailed definition:) BACTERIA (Singular: Bacterium)—Microscopic unicellular organisms, typically spherical, rod-like, or spiral and threadlike in shape, often clumped into colonies. Some bacteria cause disease, while others perform an essential role in nature in the recycling of materials, for example, decomposing organic matter into a form available for reuse by plants. Some forms of bacteria are used to stabilize organic wastes in wastewater treatment plants, oil spills, or other pollutants.
EXAMPLE:
Bacteria can exist as “good” bacteria. For example, there are 1,000 different types of beneficial bacteria in the human digestive system.
