Final answer:
A species is defined as a group of organisms that can interbreed and produce fertile offspring; it's a crucial concept in understanding biodiversity and speciation.
Step-by-step explanation:
The concept of species is fundamental to understanding biodiversity and speciation. A species is defined as a group of individual organisms that interbreed and produce viable, fertile offspring. This reproductive compatibility ensures that members of the same species can exchange genetic materials and produce functional offspring, thereby maintaining the continuation of the species. This definition restricts species from interbreeding with other species to produce fertile offspring. The concept is crucial in studying how new species form, with reproductive isolation being a key factor. Sometimes, species can be similar enough to produce hybrid offspring, but usually, these hybrids are not fertile, suggesting a speciation process in flux.