Imagine you have $1,000 to invest. Buying a diversified portfolio of stocks and bonds on your own would be expensive and time‑consuming. Now imagine pooling your money with thousands of other people, hiring a professional manager, and instantly owning a slice of hundreds of different securities. That is the simple, powerful idea behind investment companies. This chapter explains the different types of pooled vehicles — how they work, what they cost, and how they can fit into your portfolio.