Do not judge a book by its cover for all that glisters is not gold. How can you not though, when crying out to you from the cover is the proclamation that the novel is a "masterpiece" or that its writer the "voice of a generation"? Such high praise (read purple prose) comprises the blurb - that now ubiquitous presence on book covers. But the judges of the foremost literary prize in Britain have had enough. This year, the jury of the Man Booker Prize lashed out at the "outrageous" blurbs that are printed on books. These blurbs, they say, either raise the reader's expectations - more often than not brought crashing down by the book - or "blackmail" the reader into feeling "intellectually or morally incompetent" if they do not love the book as much as the writer of the blurb has. George Orwell would agree: in 1936, he had credited the decline of the novel with the "disgusting tripe" that is written on blurbs.

The curious sounding word, blurb, has served to signify various things over the decades. But it all changed in 1907 with the publication of Are You a Bromide? by Gelett Burgess, an American humorist. Burgess and his publisher found that it was common practice then to put "the picture of a damsel - languishing, heroic, or coquettish - anyhow, a damsel, on the jacket of every novel" to attract the reader's attention to it. So Burgess put on the jacket of his book a fictitious - fairly buxom - woman, Belinda Blurb, extolling the book's manifold virtues or, rather, in the "act of blurbing". The reason he chose the word blurb was that, in his mind, it was the sound that publishers made.

Burgess may have given to the blurb its most enduring meaning, but the practice of writing testimonials existed for at least a half-century before him. Walt Whitman, many believe, was its first proponent. Whitman put on the spine of the second edition of Leaves of Grass a line from the encouraging letter that Ralph Waldo Emerson had written to him on reading the first edition of the book.

Blurb writing has come a long way since Emerson wrote that letter. It has now become a veritable industry - literally. But the green lure notwithstanding, blurb writing can be tiring. Popular author, Neil Gaiman, claims that he often needs to take a hiatus from writing them. How much of what is written on blurbs do their writers actually mean though? Many admit that they write blurbs out of obligation to the author, others say they only read the first few pages before scrambling through the dictionary for adjectives. There are also those who, perhaps having run out of things to say, have written the same blurb for several books. Take, for instance, the celebrated memoirist, Frank McCourt, who has reviewed at least three books that he thinks will make the reader "claw [himself] with pleasure".

And while author, editor, agent and publisher remain locked in an intricate dance of favours called in, favours returned, favours given so that they can be reciprocated in the future, the reader blindly heads towards another " tour de force" that is not.