The term E. coli is a type of bacteria that is commonly found in the intestines of humans and other warm-blooded animals. It is a Gram-negative, rod-shaped bacterium that is part of the Enterobacteriaceae family. E. coli is an important part of the human microbiome and can be beneficial to the body in small amounts. However, certain strains of E. coli can cause food poisoning and other illnesses.