Abstract

The human microbiome refers to the large community of microorganisms, including bacteria, fungi, and viruses, that live in and on the human body. These microorganisms play an important role in maintaining normal body functions such as digestion, immune regulation, and metabolic balance. In recent years, the microbiome has gained increasing attention and is now considered an essential component of human health.
This review summarizes current knowledge about the human microbiome, focusing on its composition, diversity, and distribution across different body sites, particularly the gastrointestinal tract. It highlights how factors such as diet, lifestyle, age, genetics, and environmental conditions influence microbial balance. When this balance is disrupted, a condition known as dysbiosis may occur, which has been associated with several diseases, including inflammatory bowel disease, obesity, diabetes, and neurological disorders.
The review also discusses the role of the gut microbiota in immune system regulation, nutrient metabolism, and gut–brain communication. In addition, current therapeutic approaches aimed at restoring microbial balance, such as probiotics, prebiotics, and fecal microbiota transplantation, are outlined. Understanding the relationship between the microbiome and human health may support improved disease prevention and future microbiome-based therapies.