Mammals have fur, but are most identifiable by the fact that babies drink milk from the mother's body. They are vertebrates and have four limbs. They also are warm-blooded and breathe air through their lungs. Babies are born live as well.

There are around 5,000 known species of mammals.

One example of a mammal is a guinea pig, also known as Cavia porcellus. While these animals are domesticated pets in some parts of the world, they are a common dish in South America.

Another example is a common bottlenose dolphin, also known as Tursiops truncatus. They inhabit all the oceans of the world except for water near the poles.
http://www.nwf.org/Wildlife/Wildlife-Library/Mammals.aspx

https://media.goboard.io/mammal.html