To say this is a classic of political and social satire is unfair, because Swift INVENTED the genre with this raucous novel.
The wayward traveler - Lemuel Gulliver - ends up on a series of bizarrely populated islands. First he is a giant among little people, but then sees the situation reversed when he's surrounded by giants twelve times his size. Next he finds himself in the clouds, in a society of devoted but ultimately hapless mathematicians. Lastly, his journey brings him to an island where incredibly noble horses must deal with a race of uncouth, reviled ape-men: the Yahoos. The satire is thick and unrelenting, but certainly not specific to the time and situation when Swift wrote it, and thus it has been read and beloved for centuries.