what's an advance reader copy?

I am new to writing a book, publishing a book, editing a book, publicizing a book. I am new to all of it. I have had a ton of fun learning about it. My publicist, Jane Reilly, is the master. Thank goodness she doesn't make me feel like a dummy when I ask questions like, "What is an ARC?" So, the publisher can print very inexpensive copies of the actual book, which is known as an unedited proof. It is printed before I get to put my final stamp of approval to print the final version. Here is a photo of the ARC. Wish me luck on the journey, and pre-order your copy of the hardcover today. I'll be so grateful!