because it can be used to make people relise they have stated the obvious and it can also be used as jokes etc.
If you're seriously asking this, you paid no attention in class when you were having it read to you. Every character is satirized, you dunce.
To be able to answer your question, we would need a list of types of storytelling to choose from.
Sarcasm is saying something cutting or intended to hurt, often using irony to deliver the wound. Irony is a word used to say something other than what the words usually stand for, most often meaning the opposite of the literal meaning of the words. The tone of the voice and inflection are also often used to underscore the ironic/sarcastic part of the statement.
Examples in common speech:
A man comes to breakfast after a night of drinking, he looks hung over and is unshaven, wearing the wrinkled clothes he slept in, with hair disheveled, and his eyes are red and squinted from the sunlight.
His wife takes one look at him and says, "Well, now, don't you look just bright and shiny this morning?!"
TEEN 1: "Don't you just love brown?"
TEEN 2: "Yeah, it's like the prettiest color ever!"
^^^This is not sarcasm at all. This is exaggeration.^^^
Examples in literature: See any of Christopher Moore's works for examples of sarcasm in literature. Especially "Lamb: The Gospell of Christ's Childhood Pal, Biff"
Another extremely good example of sarcasm in literature is the character Silk in the wonderful series "The Belgariad" by David Eddings. I'm not sure if Silk is in "The Mallorean" but I know he's in the "Belgariad". Everything he says is sarcastic.
He has unrequited feelings for a lady named Rosaline, who has declared a life of chastity.
Image and Irony are some examples of figurative devices on Macbeth, a playwright by William Shakespeare. In this line by a lady in Macbeth for example says: 'The raven himself is hoarse, the croaks the fatal entrance of Duncan' in which the word raven suggests a sensation in fixing the hones of those people who had been enforced and Duncan is going to his fate.
Example:
"You weren't supposed to do that, smart one."
Explanation: You see, the person who is saying this is being rude and saying the exact opposite that they really mean by calling the other person "smart one" when they really think the person who is being spoken to is a total complete idiot. This gives a more hurtful and pointed effect.
Satire is used in works of art and literature, while sarcasm can be created without an artistic outlet
Sarcasm is using irony to make fun of something. For example, saying "I can't wait for that!" when you really mean the opposite.
An example of hyperbole is "The shark swallowed 100% of me but I managed to escape".