The story follows the journey of a girl named Alice across a strange world known as Wonderland. At first, Alice is happily living in what you or I would call the 'real' world but then she follows a talking rabbit down a rabbit hole and finds herself in Wonderland. While she's there she ends up in all kinds of weird and wonderful scenarios from playing croquet with a flamingo, to swimming through a sea of her own tears to meeting the Mock Turtle (of mock turtle soup fame).
But outside of crazy situations, part of the fun of this novel comes from its cast of peculiar characters. First you have Alice herself, she's a sweet and nice girl and acts as a kind of gateway character for us, but she's just the icing on the cake. Perhaps the most famous of all (aside from Alice) is the Hatter (and his friend the March Hare) who invite Alice to join them for a 'mad' tea party and this scene is one of the most entertaining ones, so I can see why he's well remembered. There's also the mysterious Cheshire Cat, my personal favourite, who appears (out of thin air) to have strange conversations with Alice at various parts of the story.
Something especially good about this novel is that while fairly serious things happen (there are times when Alice could actually die!) it never really makes a big deal out of anything. Even when Alice is in serious danger, it still reads like a light bit of fun, and I think this gives the whole thing a particular charm as making it all very dark would be a little cliché. I'm also pleased by how easily Alice accepts this strange world, she does think it's weird, but that's pretty much it. I find that very endearing.