A form of humorous social commentary/media meant to display criticism. Satiric posts often involves ironic uses of exaggerated and/or metaphorical imagery to highlight certain flaws of the subject.
Please note that just because it's funny, it does not mean it's satire. On the same token, just because it's a funny picture concerning a politician, it is NOT satire.
Also, please note the difference between satire and parody. Before you add the satire tag, ask yourself "Is this picture trying to prove a point?"