Superorder: Xenarthra ("strange joints")
Order: Pilosa (Latin for hairy)
Suborder: Folivora (leaf eating)
Families: Bradypodidae, Megalonychidae(living)

Sloths are well known for being very sedate mammals, hence their name. Sloths living today spend their time in trees (arboreal) consuming leaves which is a long slow process given their very slow metabolism. 

Now extinct species of sloths also lived more on the ground and had sizes similar to elephants today. 

A two toed sloth (Megalonychidae species). image: wikimedia

Some sloths are so slow that they host a wide range of other organisms from algae (which can provide camouflage)  and fungi to insects such as moths.

Sloths are native to Central and South America.