This book has quite a lot of useful info, but also a lot of jargon. You really need more basic info on the workings of web sites before fully understanding this book. However about 3/4 of the book is about telling you to get permission from the web site or network owner before testing (hacking) their facilities, which I didn't need, and to make it worse it's repeated over and over again; so as far as I am concerned the book could have been about 1/4 of the thickness. It would have been more useful to explain more about basic web site workings; although that probably is the content of 1/4 of another book?