Terminology
Sheep younger than one year are called lambs. A female sheep that is one year old is called a hogget. A female sheep any older than this is called a ewe.
A male sheep older than one year is called a ram. A gelded male sheep older than one year is called a wether.
A History of Sheep
Sheep were one of the first animals domesticated by man. They weren't overintelligent and were easy to handle because of their small size. They provided an excellent source of meat and clothing (with their wool).
During the Middle Ages they were found to be very productive, and used for their hide and milk as well.
Today, sheep are mainly raised for their meat, as wool is no longer profitable and there is not a large market for hides or sheep milk.
Sheep and Religion
It may seem strange to think that these animals would have any relation to religion of any sort. However, sheep having been domesticated for such a long time, they have roots in many of the world's major religions.
The meat of the sheep is commonly eaten by Jews and Hindus as it is an excellent alternative to pork and beef, which are tabooed by their religions.
Sikhs and Muslims both have complex ritual slaughtering tecniques.