Bacteria are amazing.
They were the first form of life to appear on Earth almost 3.8 billion years ago.
They make up the second most abundant lifeform, only outweighed by plants.
And most interesting of all: they exist in practically every environment on our planet, including areas where no other lifeforms can survive. As a result, bacteria exhibit a wide variety of appearances, behaviors, and applications similar to the lifeforms we see in our everyday lives.
The incredible diversity of bacteria goes underappreciated simply because they are invisible to the naked eye. Here, we illustrate how researchers classify these creatures on the basis of appearance, giving you a glimpse into this microscopic world.