This book is for developers. You should be familiar with any object-oriented programming language: if you understand variables, functions, classes, and objects, this book is for you. 

The programming language used in Flutter is Dart. If you've never seen Dart before, don't worry: basic knowledge of languages like Java, C#, Kotlin, Swift, or JavaScript will be enough to follow along with the projects in this book. Dart is an extremely intuitive language for developers, with a smooth learning curve.

This book is not a Dart course, but throughout the book, and in particular in Chapter 1, Hello Flutter, you'll get all you need to get started with Dart as well. 

To sum it up, if you have some knowledge of any object-oriented programming language, and want to start building great mobile or web apps with Flutter, this book is for you!