One correction for Jetifi's otherwise comprehensive write-up: Gulliver's Travels is not a children's book. Interestingly, when it first came out it was printed as Gulliver's Travels by Lemuel Gulliver - that is, it was meant to be taken as a genuine travelogue. People wrote letters outraged at the barefaced lies Mr Gulliver was telling, whilst some actually believed it! (Most, of course, got the joke.) If one examines the supposed geography of his trip it becomes clear that all the places he visits were in unknown parts of the world: noone would have known if he had visited them. Also, the ending is sufficiently dark that any wee kiddlywink would be pretty damn disturbed by it. One major part of its significance is the fact that it was one of the first major texts which played on our conceptions about authorship and the trust we place in the narrator.
Sooner or later I'll put a more detailed discussion of the book under Gulliver's Travels.