Mycorrhizas are able to colonize a wide range of environments, and this ecological success is indicative of the great diversity in the fungal endophytes’ genetic and physiological makeup. Fungal hyphae enter root cells in endomycorrhizas and form an internal symbiosis; in ectomycorrhizas, the hyphae stay extracellular. Microbes with genes that may affect the metabolism of bacteria, fungi, and plants include endosymbionts. The mycorrhizal fungus and nitrogen-fixing bacteria found in nature may make a great biofertilizer to increase crop yields while reducing the adverse effects of artificial fertilizers. In return for nutrients and water, mycorrhizal fungus receives over 20% of the carbon fixed by plants during photosynthesis. The more prevalent symbiosis, known as endomycorrhiza, is found in agricultural areas and is linked to over 85% of plants. Since they do not alter the shape of the roots like ectomycorrhiza do, they are more difficult to identify at first glance. Endomycorrhiza is of three different types: arbuscular, orchid, and ericloid. The separation and upkeep of mycorrhizal endosymbionts are the main topics of this chapter.