What is a bacterium??!

Bacteria= plural and bacterium= singular. It is a pathogen that causes disease. It invades our body and multiplies until we feel ill (we typically need aroound 100, 000 in our body until we start to feel ill). Bacteria breed best in warm, damp conditions.

The vast majority of bacteria do not affect people at all.

Some bacteria are pathogens and cause disease while there are other bacteria that are beneficial. Bacteria are responsible for making dairy products like cheese, yogurt and sour cream and it make cabbage into kimchi. We have a symbiotic relationship with many kinds of bacteria; we co-evolved; our bodies evolved to be good hosts for the bacteria and the bacteria evolved to help us. We rely on bacteria to help us digest food and bacteria makes essential nutrients like B12. In fact, observing that we actually have more bacteria cells in our bodies than human cells some suggested that people should think of themselves as colonies rather than individuals.