Blurbs, those little quotes you see on DVDs and book covers, "Wonderful book, great insight..." are the fuel for a good deal of book marketing.
Three months ago I didn't know a blurb from a blog. Now I'm seeking blurbs for my first book.
The past week I've been contacting prominent people to ask them to "blurb" book #1. (Blurb is a noun as well as a verb.) I've contacted people whose work I respect greatly, and have read for years.
When I rent DVDs I am influenced by blurbs. "Two thumbs up" by Ebert and partner, means that I rent the movie. A blurb by Joel Siegel means Do Not Rent This Movie.
When I buy books, I am influenced by reviews rather than blurbs. In fact, I can't remember ever buying a book based on a blurb.
My publisher says book blurbs are very important. I respect his knowledge of this business and until I learn differently, must assume he is right.