Hyperbole is a figure of speech in which something is intentionally exaggerated for effect.

For example, if you say "My birthday cake was as high as a mountain," you are using hyperbole to impress someone with your mother's prowess as a baker or with your own importance to rate such a cake.

Hyperbole is not difficult to recognize, whether in everyday conversation or in poetry.

In Paradise Lost, Milton wants to make sure that you are impressed with Satan so Milton says this about Satan as Satan lies on a burning lake in hell:

His other parts besides
Prone on the Flood, extended long and large
Lay floating many a rood.

A "rood" is seven yards long. "Many a" has to be at least two or three of something, so Satan is at least fourteen yards or forty-two feet high. That's as high as a four story building.

Some hyperboles are pretty shocking. Consider the following lines from "The Wrestler's Heart" by Gary Soto:

I had no choice but to shave my hair
And wrestle—thirty guys humping one another
On a mat. I didn't like high school.