Interspecific competition

In ecology, interspecific competition is when individuals of different species compete for the same resources, in an ecosystem. Examples for such resources are food, or space. Even species that never meet can compete with each other, because they need the same resources: Two kinds of predators might prey on the same animals. Interspecific competition is important, because it regulates the population of the different species. It is one of the ways natural selection happens. Interspecific competition causes evolution. 
When two individuals of the same species compete, this is called intraspecific competition.