The human microbiota represents a complex and dynamic ecosystem composed of microorganisms from various taxonomic groups, including bacteria, viruses, fungi, archaea, and protozoa. These microorganisms inhabit different anatomical regions of the human body, such as the genitourinary system, the gastrointestinal tract, the oral cavity, the skin, and the respiratory tract, exhibiting distinct densities, compositions, and functional characteristics, and interact reciprocally with the host organism. The term microbiota not only defines the diversity and abundance of microorganisms but also encompasses their functional influence on host physiology. At this point, the concept of the microbiome becomes relevant. The microbiome refers to the collective genomic content of all microorganisms comprising the microbiota, that is, their genetic material and the potential biological functions encoded by their genes. Therefore, microbiome analysis enables not only the assessment of microbial diversity, but also of metabolic capacity, signal transduction, immune regulation, and other host–microbe interactions. The microbiota and microbiome play important roles in preserving human health and homeostatic balance. A healthy microbial composition promotes immune system development, aids digestion and nutrient absorption, reduces pathogenic microorganism colonization, and contributes to the integrity of the mucosal barrier. In contrast, dysbiosis, or disruption of microbial equilibrium, has been linked to a variety of pathophysiological illnesses, including inflammatory diseases, metabolic disorders, neurodegenerative diseases, and some neoplasms. Today, microbiome research is not only essential for understanding health and disease mechanisms but also forms the foundation for innovative future medical applications.