Take a close look at your hands. A real close look. See all these microscopic critters?

Your skin is home to around 1,000 species of bacteria that make up your skin flora. Are they all bad? Do they do anything more than just make you sick?

Or do we need bacteria as much as they need us? Bacteria start colonizing your body the moment you’re born. You can’t get rid of them, no matter how many times a day you take a shower.

On average, 5 million bacteria cover every square cm (32 million per 1 square inch), of your skin. But don’t stress out – all those billions of skin bacteria combined would fit into a ball the size of a pea. You can’t even see them with your naked eye.

While some of your skin inhabitants pose serious health problems, most bacteria are not only harmless but beneficial. So what’s good about being a walking zoo? And what kind of ‘animals’ live there?

All those bacteria aren’t just taking up residence for nothing. Some of them are helping other important bacteria survive on your body, others just leave no place for harmful bacteria to settle. Then there are bacteria that alert your immune system to incoming pathogens.

Even though you can count a thousand different species of bacteria residing on your skin, there are three of them that dominate – Propionibacterium, Corynebacterium, and Staphylococcus.

Of course, bacteria don’t cover your body evenly. Just like we don’t build our homes in the coldest parts of the planet, bacteria have their own preferences when it comes to your skin.

Oily surfaces, like your face, can be much more densely populated – with up to 80 million bacteria per square cm (500 million per sq. inch). Those oily areas are called sebaceous zones, and they’re a particular favorite of Propionibacterium acnes. Yes, the ones that cause that annoying skin condition.

These bacteria live in your hair follicles and the pores of your skin, but they don’t normally cause any problems. Even if your skin looks perfect – it’s still crawling with Propionibacterium acnes.

They live deep in your pores and feed on sebum – the oily secretion that moisturizes and protects your skin and hair. But once your body begins producing too much sebum, these bacteria proliferate, clogging your pores and causing inflammation.

The genus Staphylococcus counts over 40 species of bacteria. The most common one is Staphylococcus epidermidis. These bacteria are typically harmless inhabitants of your skin, but they can cause infections associated with medical devices like catheters or implanted prostheses.

Then there are the moist zones of your skin – the creases of your elbows, your armpits and areas between your toes. They are home to Corynebacteria. Some pathogenic species of this bacteria can produce toxins and cause diphtheria. However, their non-pathogenic relatives are widely used in the mass production of amino acids. Some species even produce substances similar to antibiotics.

It’s kind of gross to think of just how many bacteria are crawling on your hands, neck, and face while you’re living your life. But they are a part of you.

There’s a whole bacterial civilization using your skin as land. You should feel good about it. For them, you are their whole world.

And it’s not just your skin that bacteria call home. In fact, half of the cells that make up your body aren’t human cells. They are bacterial ones.

While there are 1,000 types of bacteria covering you from head to toe, there are even more types to be found inside your mouth – over 1,200 of them. Ew.