That's a dedication. (The dedication of your first book, we assume). But don't get too excited, it's not that easy. Back in the day—we're talking when books first started being printed in the late 15th-century—dedications were super long. Why? Because authors had to do everything in their power to suck up to the people paying to produce their book (their patron). Plus, it gave them a chance to show off a bit for everyone else who laid eyes on it.
Dedications existed even before print—in the good old days of the manuscript—but then, only one-ish person would get to read what the author wrote. With print, an international body of readers was on the scene.
These sly little suckers can show up anywhere in a text. Our buddy Dante dedicated his Vita Nuova to his best friend—but the dedication was right smack dab in the middle of the book. These days, though, things are a little less tricky. The dedication is usually right there at the beginning of the book or poem, like in Allen Ginsberg's Howl.
And don't forget, works of literature can be dedicated to groups of people (like in The Things They Carried), places (like in The Absolutely True Diary of a Part-Time Indian), or anything else that strikes the author's fancy.