The gut microbiota has been referred to as the hidden metabolic "organ" due to its enormous impact on host metabolism, physiology, nutrition, and immune system. The relationship between the gut microbiota and the animal host is complex, changing, and generally mutually beneficial. As this relationship is complex, strategies have been studied to help modulate the microbiota to result in greater health and performance. Feed supplementation with biotic products is one of these strategies. These supplements have indirect effects via the manipulation of the quality of the microbiota and an improvement in the intestinal epithelial barrier. In addition to these functions, a stimulation of the host's immune system, a decrease in the colonization of pathogens and relief from stress have also been reported. Therefore, these supplements are presented as a safe alternative to the use of antibiotic growth promoters. The objective of this review is to know what biotic products are and how they work, as well as their application in animal production.