Hi there!
Both phrases are natural, but they have different meanings:
- "According to the book" means based on what the book says.
- Example: According to the book, pandas eat mostly bamboo.
- "By the book" means following the rules or instructions strictly.
- Example: The police officer did everything by the book.
So, if you’re referring to information from a book, use "according to the book." If you mean following rules or procedures exactly, use "by the book."
Tip: When choosing between similar phrases, think about their meaning in context. "According to" is used for reporting information, while "by the book" refers to following rules strictly. Understanding these subtle differences will make your English sound more natural!
Hope that helps! Let me know if you have more questions.