These Canker Sore pictures will give you some examples to show you what Canker Sores can look like.
Here's a canker sore at the top of the inside of the lip.
Here's a really bad canker sore right in the middle of the inside of the lip.
Here's a painful canker sore on the side of the tongue.
Here's a canker sore on the back of the tongue.
This guy has two canker sores, one on each side of his mouth.