The Little Book of Common Sense Investing, written by John C. Bogle, is a guide to passive investing and index funds. The book emphasizes the importance of low-cost, diversified investing and highlights the pitfalls of active trading and market timing. It provides a straightforward approach to investing that is accessible to both beginners and experienced investors. The Little Book of Common Sense Investing is a must-read for anyone looking to build a solid investment portfolio without the need for extensive research or stock picking.