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Your body is home to trillions of bacteria, especially in your gut, mouth, and on your skin. Most of these bacteria are harmless or even helpful. They assist with digestion, produce certain vitamins, and help protect against harmful microbes. Scientists call this community of microorganisms your microbiome.
Keeping it healthy is an important part of overall health. You're never truly alone—your body is home to an entire microscopic ecosystem.
© National Institutes of Health