Let us remember that a satire is a work of literature that deliberately uses irony and exaggeration to point out the social foibles or failings of a character, institution or group of people, normally in the hope of provoking some form of change. Austen in her writings is an excellent satirist, as she takes the conventions, expectations and cultural norms of her day and uses exaggeration and irony to great effect in order to hold a distorted mirror up to her society, so that they see themselves for who they are but in a more distorted fashion.
With this in mind, let us consider the first sentence of this brilliant novel:
It is a truth universally acknowledged that a single man in possession of a good fortune must be in want of a wife.
Of course, we can immediately note the exaggeration in this opening. Austen does not seriously expect us to believe that every single wealthy man is desperately searching for a wife, she is talking about the expectations of society and how women like Mrs. Bennet are so desperate to marry off their daughters well that they make such assumptions. If we consider the next paragraph, this exaggeration and irony is shown to continue:
However little known the feelings or views of such a man may be on his first entering a neighbourhood, this truth is so well fixed in the minds of the surrounding families that he is considered as the rightful property of some one or other of their daughters.
This indicates that even before men such as Mr. Bingley are known, families are busy staking their claim to him, presenting us with a ludicrous situation. Austen thus through her first sentence satirises the marriage habits of her society, clearly indicating the way in which single men are considered "up for grabs."