Prerequisites

The only true prerequisite for this book is a camera and a willingness to use it. Everything else is taught from the ground up.

What you need

A camera — any camera. A smartphone counts, completely. So does an entry-level mirrorless or DSLR, a point-and-shoot, or a professional body. The book is written to be done on whatever you own, and every technique includes a path for phone-only readers. You do not need to buy anything to start.
A way to see your photos at a reasonable size — a computer, tablet, or even the phone screen — so you can review what you shot and learn from it.
For some later chapters, free or low-cost editing software helps (the book stays software-agnostic and explains the principles, not one product). A phone editing app is enough for the mobile path.

No prior photography education. We start from "this is what a lens does."
No art background. Composition and color are taught as learnable skills, not innate talent.
No physics, optics, or math beyond arithmetic. Aperture, exposure, and the inverse-square law are taught with diagrams and ratios, never derivations. The deeper science lives in optional 🔬 The Physics boxes you can skip entirely.
No expensive gear. This is, in part, a book-length argument that you already have enough camera to make excellent photographs.

Basic comfort with your device — installing an app, changing a setting, moving files around.
A habit you will build as you go: shooting regularly. Photography is a physical, repeated skill. The readers who improve fastest are the ones who do the 📸 In the Field assignments rather than just reading about them.
Curiosity about light. If you have ever noticed how a room looks different at 9 a.m. and 5 p.m., you already have the instinct this book will sharpen into a skill.

If you have a camera of any kind and ten minutes to go outside, you are ready. Turn to Chapter 1.