If you check out the list of the top selling books on Amazon in the Investment category, you would see that the investing related book at the top of group is The Intelligent Investor: The Definitive Book on Value Investing. A Book of Practical Counsel by Benjamin Graham. The book was written over 65 years ago, back in 1949.
The book is considered a classic. The approach that Graham covers is value investing on a long term basis, while minimizing risk and loss. Here is what Warren Buffett has to say about the book: "By far the best book on investing ever written."
Amazon readers like the book also, giving it an overall average rating of 4.5 stars. If you are an investor, and haven't read The Intelligent Investor, you really need to get a copy and read it.