well readers, Everyone has used metaphors in some form or other, whether they realized it or not. You might have described someone as having a heart of stone or ice, or you might have claimed to have a broken heart after a bad breakup or losing a loved one. You might have even said you had cabin fever after staying inside all winter doing nothing much but staying warm. However, there are some metaphors that are used that aren’t as well known, or you might have heard a metaphor used in a way that didn’t seem to make sense to you. The definition of a metaphor is "a figure of speech containing an implied comparison, in which a word or phrase ordinarily and primarily used of one thing is applied to another. For example, "the curtain of night" or "all the world's a stage."All these expressions have one thing in common: a situation is compared to a real thing, although the situation is not actually that particular thing.

Purpose of Metaphors

Expressions are used to give effect to a statement. Metaphors are meant to create an impact in the minds of readers. The aim of this literary tool is to convey a thought more forcefully than a plain statement would.They are exaggerated expressions no doubt, but they are exaggerated because they are supposed to paint a vivid picture, or become a profound statement or saying.

Metaphors can be classified in a range of different ways, based on various criteria, from complexity to level of usage.

• Absolute metaphor: Separated subject and vehicle.
• Active metaphor: New and not established.
• Complex metaphor: Multi-layered.
• Compound metaphor: With many parts.
• Dead metaphor: Normal language, no longer recognized as metaphor.
• Dormant metaphor: Weak connection between vehicle and subject.
• Dying metaphor: Unfashionable
• Extended metaphor: One subject, many sub-elements.
• Implicit metaphor: Incomplete description.
• Mixed metaphor: Mismatched combination of metaphors.
• Pataphor: Extreme form of metaphor.
• Root metaphor: Unrealized basic driver.
• Simple metaphor: Single meaning and linkage.
• Submerged metaphor: Use a part as a metaphor for something else.
• Synechdochic metaphor: Use a part as metaphor for the whole.
  

References http://examples.yourdictionary.com/metaphorexamples.html#mp9l5boPxHPuIsSS.99