What is satire in a general sense and what is its purpose?

The purpose is fall of anything or anyone is a cause for humour, something to laugh at, something to laugh about. Satires make use of this principle. But a satire it is not a mere humorous poem, but pure social criticism made immortal by attiring it in the form of poetry. Satires bring human mind to the loweliest of things or attitudes described in them, but their ultimate purpose like all other poetic forms is to elevate human mind. Cleverly cunning descriptions of those base and lowly things and attitudes give us glimpses of what is loftiness in such matters. That is the way the satires attain their purpose.

It is a denunciation of vices, folly or abuses of any kind by the means of sarcasm, derision or ridicule.