It is a type of interaction between species for nutrition and shelter.
The interaction may be positive in which both get benefited or negative in which both may not get benefited
Symbiotic nutrition can exhibit in following ways:
Mutualism: It is a type of interaction in which both are benefitted by an obligate association (eg: Rhizobium in the roots)
Commensalism: It is a type of interaction in which one gets benefitted and another one neither benefited nor harmed (eg: Epiphytes which are grown on the trees)
Parasitism: It is a type of relationship in which one organism get benefitted and another one is harmed (eg: Leeches)