As a bookseller, I spend a lot of time answering this question:
"What's this book about?"
Sometimes this is easy to do, and sometimes it isn't. Let me give you an example of a book that you're probably familiar with... Mike Mulligan and His Steam Shovel.
What's it about? Well, we can take the easy route and say it's about a guy named Mike who has a steam shovel. But, that's obvious from the front cover and it doesn't really answer the question. More importantly, it doesn't make anyone want to read the book.
Here's a better answer: "It's about a man and his steam shovel who try to dig the cellar of a town hall in just one day. It's a classic and it was one of my favorite books when I was younger."
Why would my answer be so short? Why didn't I go into what else Mike and Mary Ann did, and talk about digging four corners nice and square, and how much I love Virgina Lee Burton's books? Because, time is of the essence. Most people want a quick summary, not a review. And usually we're discussing two, three or ten other books.
If I have good feelings or memories about the book, I'll usually mention that. It helps give a frame of reference. In this case, the fact that I read it when I was younger points out that the book has stayed in print for a while. And with Mike Mulligan, I usually say that loved it when I was a little girl, because people are often hesitant to buy a book for a girl with construction equipment on the front cover. (For more about Mike Mulligan and His Steam Shovel, which really is a terrific book, see this post.)
Picture books are pretty easy because people can sit down and read them right in the store. But try summing up Good Night Moon. "It's about a bunny who says good night to every object in his room before falling asleep." Doesn't exactly grab you, does it?
Chapter books are even harder to describe quickly and effectively. Plus, you want to introduce the plot without giving any of it away. Here's a question I was asked a few months ago that I had a surprisingly hard time with:
"What's the Lord of the Rings trilogy about? I don't want a lot of detail, just give me the general idea in two sentences."
Wow. Um, okay. Summarize hundreds of papers and complex writing in two sentences? What would you say? I think I said something to this effect:
"It's about a small, insignificant creature (a hobbit) who has come to possess a magic ring, which is the most powerful object in the world. He has to travel to the other end of his universe to destroy it, and the books are about his amazing journey."
Remember, you've got to do these summaries on the spot... and you want to do the books justice. It's not enough to use the summary on the back of the book or the dust jacket or the Library of Congress notation... people can read those for themselves. They want to hear someone talk about the book.
Can you describe Charlotte's Web in a few sentences that would make me want to read it? How about Mr. Popper's Penguins? Harry Potter? Anne of Green Gables? Pride and Prejudice? The Wizard of Oz? Charlie and the Chocolate Factory? I've been asked the "what is this book about" question for all of the books mentioned above... usually from a person who hasn't heard of the book before. And I recently got asked what Mother Goose rhymes were. It can sometimes be difficult to put aside the history and reputation of the book or poems, and just state the basic plot in an intriguing way.
Try the book I've been asked about all week: The Invention of Hugo Cabret. (I wonder why I've been asked about it so much. Could it be the fact that I've displayed it in every available space in the store?) For Hugo, I usually show people the first page... and it's pretty hard to put down after the fantastic introduction. But I don't have a really good short summary of it yet. Currently, I've been saying something along these lines (while flipping through the book to show off the pictures):
"It's about an orphan boy who lives in the walls of a train station in Paris and makes a tremendous discovery. The book is a unique combination of pictures and words and when you read it, you feel as though you're watching a movie."
Needs work. Got any suggestions?