Cats are members of the family Felidea.  They are pure carnivores and require a high level of protein in their diets (about 30%) and lack the digestive equipment to survive on a diet of grains, fruit, or vegetables.  They are hunting mammals, equipped with powerful jaws, sharp teeth, and claws that draw back into their paws when not being used.  They have extremely acute hearing and their eyes easily adjust to darkness for hunting reasons.

Contrary to popular belief, cats are very social animals.  It is always thought that dogs need lots of attention while cats would rather be left alone.  This is very much not true, as cats love and crave attention.  However, they prefer attention when they choose, so it is easy to understand how they have gained this reputation of being aloof.  Unlike dogs they do not suffer from lonliness, but they can get depressed in some cases  when lonely and act out.

Cats without apparent pedigree are generally referred to as "Domestic Shorthairs" or "Domestic Longhairs," depending on their coat length.  Domestics have a wide range of appearances, coming in many combinations of colors, both in coat color as well as eye color and varying temperments. 

A Brief History of Today's Housecat

50 million years ago:  The Miacis The Miacis was a small animal that lived in trees and is the oldest known ancestor of the cat, dog, and other animals such as the bear, weasel, raccoon, and fox.  The Miacis had a long body, even longer tail, and short legs.  It also probably had retractable claws like today's domestic cats.
40 million years ago:  The Dinictis The Dinictis was a very agile animal on both the ground and in trees.  It was a small primitive cat with a sleek body, a long tail, and short legs.  It is also known as a "false saber tooth" because of its long saber teeth.
1500 BC:  Egyptian Deities Cats during this time were captured from the wild as kittens to grow up domestically for the first time.  They were at first used to help hunt, but were later worshipped as deities.  Protected by the law, anyone who harmed or killed a cat was punished harshly.  Cats were mummified after death, and owners shaved off their eyebrows to display mourning.
900 BC:  European Mousers Phoenician traders traveling to Europe used cats to catch rodents.  Soon they gained this reputation and were popular across Europe.  The tendency of cats to do their own thing made them mysterious, and they were worshipped in different everyday and religious rituals.  However, this was not the same as in Egyptian times.
Devil of the Middle Ages Cats were associated with the Norse goddess, Freya.  When Christianity barred her worship, she became a demon.  Friday became known as the Black Sabbath and the cat became associated with the devil.  Many were tortured and killed.  The cat population shrunk to only ten percent of its original size, aiding to the spread of the Black Plague, which was caused by fleas on rats.
17th Century:  Rodent Controllers Cats began to regain their status as rodent catchers and were employed on ships after the Black Plague due to their increased popularity after managing to control the rat population once again.  They were seen as important members of the crew rather than pets, and they were treated as equals.  Many ended up in America after crossing the ocean.
18th Century:  Popular Pet Cats became popular pets, serving not only as rodent catchers but as companions also after reaching America.  Today they are a very popular pet in America, Europe, and many other countries around the world.  Some still believe in their former stereotypes and see them as royalty or demons, but to most they are just a clever companion.