by the book: meaning and explanation
If you do something by the book, then you follow all the rules and regulations that you are supposed to. You don’t cheat, take shortcuts or ‘bend the rules’.
This expression can be used in a neutral or positive way (as with the first micro-dictation), but can also be used as a way of criticising someone for being inflexible and unprepared to do things in an unconventional way. e.g. If you’re looking for someone to come up with a creative solution to this, then don’t bother asking Mike. He always does everything by the book.
Have a go at these micro-dictation exercises to hear this expression being used in context – how much can you understand?