Let's start at the bottom shall we? What exactly is this pig you speak of?

A picture speaks a thousand words, so we'll start with this:

Pig, hog, swine. A male pig is a boar, a female pig is a sow, and a baby pig is a piglet.

Pigs live on every continent on Earth apart from Antarctica, they adapt very well to different environments and can survive on a huge variety of foods (another similarity pigs have with humans).
Thousands of years ago pigs were all wild, nowadays they are domesticated and are farmed for leather (using their hides) and meat.
Pigs can be a range of colours: Black, white, brown, pinkish. Some have tusks which they use for fighting and/or digging for food.

Goats, sheep and cows are all in the same family as the pig; Mammalia, Artiodactyla (even-toed hoofed mammals).