Adam Silver’s stuff is great and so is this book. I found some of the code samples a little outdated and browsers have improved since this was written, so some of the workarounds he mentions are no longer necessary. That said, this book’s fundamentals of clear and easy-to-use form design are still rock solid. I strongly recommend it for anyone who builds forms on the web.

Also, check out the UK digital service’s design systems and guidelines. Adam worked on these at one point and they’re an invaluable resource.