What's a query letter?

My cousin asked me this question on Facebook, and it occurred to me that maybe I haven't been very clear on what, exactly, a query letter is.

Ahem.  (Picture me standing up straight and speaking in my best professional presenter's voice.)

A query is a letter you write to a literary agent in the hopes that your concise, witty description of the book you've spent more than a year slaving over will entice him enough to request the manuscript.

You will send this letter via email or snail mail, depending on the agent's preference.  You will not forget to personalize the letter to include the agent's name, spelled correctly.  Nor will you forget to include a self-addressed stamped envelope (if querying by regular mail) for the agent's convenience, should the agent be so crazy as to reject you.

Once the letter is sent, you pray that the agent will love the premise of your story and ask to read the manuscript in its entirety.  Which, since he's not crazy, he will.

You will then send him the manuscript pronto (properly formatted using Times New Roman or Courier New 12-point font double-spaced with one-inch margins, with your name, the title, and the page number at the top of every sheet, hard copy or electronic, whatever he prefers) hoping he'll fall in love with the book and agree to take you on as a client.

Once the contract is signed, the agent will shop your book to all the publishing houses in New York City, generating a bidding war amongst the top five, because yes, your book is just that good.

Which will then result in the sale of the book for hundreds of thousands of dollars, allowing your spouse to quit his day job so the two of you can buy a villa in Tuscany.

Then, while you're leisurely writing the next fabulous novel (in your backyard, surrounded by grapes and olives which are lovingly cared for by your gardener, Benito, whose perfect abs make you crave chocolate because you're married) your book will generate incredible sales in every bookstore in the world, inevitably catching the attention of Hollywood.

A big wig movie production company will then option your book for few hundred thousand more, allowing you to buy a bigger villa in Tuscany (and another Benito).

And, since the movie will star Brad Pitt, Angelina Jolie and Jennifer Aniston, you'll become even more famous, and your next book will sell for a cool seven figures.

In sixty years, after more than thirty bestselling novels, you will die peacefully surrounded by your children, grandchildren, housekeeper, chef, chauffeur, personal massage therapist, and the two Benitos, knowing you've made your mark on the world and that there's a special place in heaven for brilliant fiction writers.

That's the idea, anyway.

In reality...

A query is a story-hyping, excitement-generating, typo-free one-page letter full of exceptional, original prose that you send to an Awesome Literary Agent Who's Never Heard Of You, who'll glance at it for ten seconds, then send you a soul-sucking, self-esteem crushing rejection letter that rips your dream of being a published novelist to shreds, sending you head first into a depression you can't get out of for days.

In a nutshell.

(I got my first rejection today.  It's possible my explanation is a bit off.)