The dedication usually goes on the dedication page, which is in the very front of the book, after the Title page.
https://www.youtube.com/watch?v=7KZhFzinTY4
Here are the categories of people that are common focuses of a book dedication:
Many people write their book dedication to a child or dedicate their book to a friend who's impacted their creative process. There’s no magic formula. This should be short and sweet, and there are no wrong answers. You are expressing a personal sentiment, so only you can decide.
The worst thing you can do is get stuck on it. Either do it or don’t. If you decide to have one, don’t fret over it. Go with your gut. Anyone you leave out can be thanked in the Acknowledgments (which goes at the end of the book).
And yes, though everyone will see it, no one but the person you mention will remember it. Want proof? Name your favorite book dedication. Chances are you can't name one.
That is what the Acknowledgements is for (if you want).
Most of them as very basic and simple, something like this:
For my wife Megan and children, Ava, Jaxon, and Elle.
George R. R. Martin, who wrote the Game Of Thrones series, has a unique dedication in A Song of Ice and Fire:
For Phyllis, who made me put the dragons in.
This concise line holds enormous depth for both the readers and the person mentioned. If you’ve read the books or seen “Game of Thrones”, you’d know that dragons and the fantasy world they represent were a big part of the appeal. To imagine the book without them would be nearly impossible. Phyllis clearly played a big role in the creation of this piece (it’s also an inside joke for fans).
Here’s the dedication that C. S. Lewis wrote to his goddaughter in The Lion, The Witch, and the Wardrobe:
My dear Lucy,
I wrote this story for you, but when I began it I had not realized that girls grow quicker than books. As a result you are already too old for fairy tales, and by the time it is printed and bound you will be older still. But someday you will be old enough to start reading fairy tales again. You can then take it down from some upper shelf, dust it, and tell me what you think of it. I shall probably be too deaf to hear, and too old to understand a word you say, but I shall still be your affectionate Godfather,
C. S. LEWIS
This book was listed as one of TIME Magazine’s Top 100 Novels ever written, and yet he wrote it for his goddaughter. This dedication gives real substance to the book, and the author, before you even dive in.
This next example is a short-and-sweet dedication from a book I co-wrote with Dr. Geoffrey Miller:
To our 17-year-old former selves, and to Bishop, Atalanta, and all the sons and daughters who deserve the great relationships we want for them.
One of our Author's fans often look forward to his dedications, because they are so colorful, and in some cases, even part of the book. For example, from his book Anansi Boys:
You know how it is. You pick up a book, flip to the dedication, and find that, once again, the author has dedicated a book to someone else and not you.
Not this time.
Because we haven't yet met/have only a glancing acquaintance/are just crazy about each other/haven't seen each other in much too long/are in some way related/will never meet, but will, I trust, despite that, always think fondly of each other...
This one's for you.
With you know what, and you probably know why.
The dedication at for The Little Prince by Antoine de Saint-Exupery is somewhat famous:
TO LEON WERTH
I ask the indulgence of the children who may read this book for dedicating it to a grown-up. I have a serious reason: he is the best friend I have in the world. I have another reason: this grown-up understands everything, even books about children. I have a third reason: he lives in France where he is hungry and cold. He needs cheering up. If all these reasons are not enough, I will dedicate the book to the child from whom this grown-up grew. All grown-ups were once children—although few of them remember it. And so I correct my dedication:
TO LEON WERTH WHEN HE WAS A LITTLE BOY
Charles Bukowski in his book Post Office plays off the banal nature of most dedications by saying this:
This is presented as a work of fiction and dedicated to nobody.
There is a book called The Selection by Kiera Cass that has gotten some notoriety online with this book dedication:
Hi, Dad! *waves*
What’s inside of your book is more important, and getting it out into the world is the MOST important thing.