Definition: Interbreeding – infertile and fertile offspring
A species is a group of organisms capable of interbreeding - producing fertile offspring, and does not usually breed with other groups.
Interbreeding with two different species – they can breed but will produce infertile offspring. For example, a lion and a tiger can breed, and their offspring are called Liger. However, Ligers can't reproduce because they are infertile.
Interbreeding and fertile offspring – for example, finches can breed because they have similar characteristics.