Microbiome refers to the aggregate genomes of the microbes in a given environment, whereas microbiota refers to the community of microbes. In the human gastrointestinal system, there are around 100 trillion microorganisms (mostly bacteria, but also viruses, fungi, and protozoa)—the microbiome is currently best thought of as a virtual organ of the body. The gut microbiota, a diverse and dynamic collection of microorganisms found in the human gastrointestinal (GI) tract, has a significant impact on the host during homeostasis and disease. Several variables have a role in the development of the human gut microbiota during childhood. The microbiota of the intestine can be defined as a collection of bacteria groups. The gut microbiota plays a number of important roles in the metabolism of the host. To maintain healthy body functions, a long-term relationship between the gut microbiota and the host is required. The gut microbiota is also involved in the harvesting energy from food and may have a role in the development of obesity.