Satire:
A work that targets human vices and follies or social institution and conventions for reform or ridicule. Regardless of whether the work aims to reform humans or their society, satire is the best seen as a style of writing rather than a purpose of writing. It can be recognized by the many devices used effectively by the satirist, such as irony, wit, parody, etc. Good satire is generally humorous  is thought provoking and insightful about the human condition.

Example:
""Ain't they no Shepherdsons around?" They said, no, 'twas a false alarm.  "Well," he says, "if they'd a ben some, I reckon I'd a get one.""
-Adventures of Huckleberry Finn

Explanation:
This is an example where, Buck, a Grangerfield is talking about shooting a Shepherdsons. The purpose of this is because Twain is making fun of the Civil war, saying they are fighting for no reason. It also can be seen as satirical towards southerners because they can go from sweet, to bitter and revengeful in a heart beat.