And they lived happily ever after...
Paranormal Romance (PnR) is first, Romance. There is the obligatory happy ending, which let's face it, is a big draw in today's world. It allows escape and a sense of safety. We all know where we'll be at the end. If you add to that the paranormal, the escape is truly out of this world.
There are a few definitions floating around. Two of the more accessible are from Wikipedia and Juno Books. Another good resource is PNR (ParaNormalRomance.org). I'm sure there are more out there, but these came to mind first.
A more formal essay from Juno Books editor Paula Guran can be found, in pdf, on the Juno website. Introduction: What is "Paranormal Romance"? is a fairly in depth look at the history of PnR. It's worth a read, as well as the book in which the essay was published, Best New Paranormal Romance.
The important elements in this genre are romance and of course, paranormal. Paranormal encompasses fantasy, the unexplained, the mystical, psychic abilities, horror, and sci-fi. Anything from Buffy the Vampire Slayer to Stargate to X-files fits the bill.
But really, let's not forget that PnR lets the cave men back out. Big alpha-male shape shifters. Sword toting female warriors. Lots of sweaty, steamy sex. This genre tends toward steamy to downright erotic. While the author is taking you out of this world, setting you up for a happy ending, the sexual fantasies get satisfied as well. Think Sherrilyn Kenyon, Christine Feehan, and Lori Foster is jumping in, under the name L.L. Foster.
Speaking of sword totin' women, the before mentioned Juno Books is looking for good published short stories with female warriors, for an anthology. Can't wait!
To wrap it all up, PnR is basically fantasy wrapped in a sexy package with six-pack abs.