The lines covered in this book, the Ruy Lopez Main Lines, arise (with a few exceptions for move order and such) after 1 e4 e5 2 Nf3 Nc6 3 Bb5 a6 4 Ba4 Nf6 5 0-0. Some of the lines are incredibly theoretical, but rather than burden you with a ton of theory in lines you will have limited chance of using in your own games, the emphasis is on the lines that are more likely to occur in your games. Those lines will be in chapters 3 and 4, the two longest chapters of the book. This book is by no means an all-encompassing theory work, which means that there is a lot of theory that is not discussed in the notes. This is of course intentional. The book is written to entertain and inspire. If you find some lines that you like, you are encouraged to dive deeper into those lines before using them in your own games.