Mutual funds are an easy, convenient way to invest, without having to worry about choosing individual stocks. A mutual fund can be defined as a single portfolio of stocks, bonds, and/or cash managed by an investment company on behalf of many investors. The investment company manages the fund, and sells shares in the fund to individual investors. When one invests in a mutual fund, they become a part-owner of a large investment portfolio, along with all the other shareholders of the fund. The fund manager invests the contributions when shares are purchased, along with money from the other shareholders.