The relationship between gut microbiota and inflammatory bowel disease (IBD) remains a topic of debate, with evidence suggesting a complex interplay between microbial composition and disease. While IBD is associated with dysbiosis—reduced microbial diversity and altered microbial balance—direct causation has not been definitively proven in humans. Animal models have shown that gut microbiota can influence both health and disease, with some bacteria promoting inflammation while others may have protective effects. However, chronic inflammation can also shape the microbiota, contributing to dysbiosis. Studies have shown differences in gut microbiota composition between IBD patients and healthy individuals, with specific bacterial taxa, such as Faecalibacterium prausnitzii and Enterobacteriaceae, being more prevalent in IBD. These findings suggest that dysbiosis may precede clinical disease and develop independently of long-standing inflammation. However, the exact role of dysbiosis in IBD pathogenesis is still unclear, as studies have struggled to determine whether it is a cause or a consequence of inflammation. The microbiome includes not only bacteria but also fungi and viruses, and their roles in IBD are increasingly recognized. Fungal dysbiosis has been associated with IBD, with certain fungal species, such as Candida albicans, being more prevalent in affected individuals. However, the causal relationship between fungi and IBD remains uncertain. Microbial metabolites, such as short-chain fatty acids, also play a role in IBD pathogenesis. Changes in microbial composition can lead to alterations in metabolite production, which may influence immune responses and inflammation. The gut microbiota also influences immune function, with studies showing that germ-free mice have impaired immune development and that antibiotics can affect the microbiota and immune response. Animal models have been instrumental in understanding the role of the microbiota in IBD, revealing complex interactions between the immune system and the gut microbiota. However, these models have limitations, and their findings must be interpreted with caution when applied to human disease. In conclusion, while the gut microbiota is likely to play a significant role in IBD pathogenesis, the exact mechanisms and the extent of its influence remain to be determined. Further research is needed to clarify the relationship between the microbiota and IBD, and to develop effective therapeutic strategies based on microbiota-targeted interventions.The relationship between gut microbiota and inflammatory bowel disease (IBD) remains a topic of debate, with evidence suggesting a complex interplay between microbial composition and disease. While IBD is associated with dysbiosis—reduced microbial diversity and altered microbial balance—direct causation has not been definitively proven in humans. Animal models have shown that gut microbiota can influence both health and disease, with some bacteria promoting inflammation while others may have protective effects. However, chronic inflammation can also shape the microbiota, contributing to dysbiosis. Studies have shown differences in gut microbiota composition between IBD patients and healthy individuals, with specific bacterial taxa, such as Faecalibacterium prausnitzii and Enterobacteriaceae, being more prevalent in IBD. These findings suggest that dysbiosis may precede clinical disease and develop independently of long-standing inflammation. However, the exact role of dysbiosis in IBD pathogenesis is still unclear, as studies have struggled to determine whether it is a cause or a consequence of inflammation. The microbiome includes not only bacteria but also fungi and viruses, and their roles in IBD are increasingly recognized. Fungal dysbiosis has been associated with IBD, with certain fungal species, such as Candida albicans, being more prevalent in affected individuals. However, the causal relationship between fungi and IBD remains uncertain. Microbial metabolites, such as short-chain fatty acids, also play a role in IBD pathogenesis. Changes in microbial composition can lead to alterations in metabolite production, which may influence immune responses and inflammation. The gut microbiota also influences immune function, with studies showing that germ-free mice have impaired immune development and that antibiotics can affect the microbiota and immune response. Animal models have been instrumental in understanding the role of the microbiota in IBD, revealing complex interactions between the immune system and the gut microbiota. However, these models have limitations, and their findings must be interpreted with caution when applied to human disease. In conclusion, while the gut microbiota is likely to play a significant role in IBD pathogenesis, the exact mechanisms and the extent of its influence remain to be determined. Further research is needed to clarify the relationship between the microbiota and IBD, and to develop effective therapeutic strategies based on microbiota-targeted interventions.