The rhizosphere is the narrow region of soil that is directly influenced by root secretions and associated soil microorganisms known as the root microbiome. The rhizosphere contains many bacteria and other microorganisms that feed on sloughed-off plant cells, termed rhizodeposition,and the proteins and sugars released by roots. This symbiosis leads to more complex interactions, influencing plant growth and competition for resources. Much of the nutrient cycling and disease suppression needed by plants occurs immediately adjacent to roots due to root exudants and communities of microorganisms.The rhizosphere also provides space to produce allelochemicals to control neighbours and relatives.The plant-soil feedback loop and other physical factors are important selective pressures for the communities and growth in the rhizosphere.