For me, it's the "Rich Dad, Poor Dad" by Robert Kiyosaki. It's the first book I've read about money and investing. It told me that I don't need to earn huge in order to become rich but instead I should be wise where or how to spend my money.

It's a good book to read as a starter since the words used are not deep amd the story between two fathers is engaging that will get you hooked to read it continuously.