A species is a group of similar organisms that can breed with one another to produce fertile offspring. For example, humans are one species and dogs are another species.

Individuals of the same species can reproduce to make more individuals of the same species. Two individuals belonging to different species cannot normally reproduce together. If they do, their offspring is often infertile and unable to reproduce.

A pair of Emperor penguins (Aptenodytes forsteri) courting
These penguins belong to the same species

Nicola Mallott from Knowsley Safari Park explains the five species of rhino - the White, Black, Indian, Javan and Sumatran.

Sometimes individuals from two different species can reproduce. For example, animals called ligers are produced when a male lion and a female tiger reproduce. Tigons are produced when a female lion and male tiger have cubs. Unlike many young from different species, ligers and tigons can have offspring.

A liger, the product of crossbreeding a male lion and a female tiger
A liger looks like a lion but has stripes like a tiger