An exaggeration of ideas for emphasis or effect of an overgenerous statement for amusement is called Hyperbole. Hyperbole has amusing effects created by an overstatement to induce strong feelings or to create a strong impression, but is not meant to be taken accurately. In short, Hyperbole's are exaggerations to create highlighting or effect. Hyperbole's can be used to better express an author’s intentions and meaning when used in a proper context. Often, Hyperbole is identified by trigger words such as "most," "best," or "worst."

Examples of hyperbole are:

Her brain is the size of a pea.

I could sleep for a year; I was so tired.

I am dying of shame.

My grandmother is as old as the dinosaurs.

I've told you a million times to complete daily homework’s.

I can smell death by chocolate ice cream from a mile away.

Functions of Hyperbole

Hyperbole, like other figures of speech, is used to connect ideas, thoughts, emotions, and images in a more effectual way than through plain language.

Hyperbole's can often be combined successfully with similes and metaphors to surge their effectiveness, although common phrases must not be repeatedly used to avoid being in a cliche.

Information, emotion, or statements are exaggerated intentionally for an assured effect.

The exaggeration serves to accentuate a specific point.

In prose, hyperbole is used for the purpose of importance or for humor.

To describe an action that is significant in some way.

Hyperbole can be used in descriptions to highlight some prominent features of a character.

To place emphasis on a particular act, feeling, or feature and not taken literally.

Homer’s epic poems “The Iliad” and “The Odyssey” are prime examples of the use of hyperbole in poetry.

Reference: http://english.tutorvista.com/literary-response/hyperbole.html