Income investments include bonds, certain stocks, and other investments that generally pay periodic interest or income, but whose principal value may vary daily. Equity investments include most stocks and other ownership investments whose principal values vary daily but have potential for future growth. If we have missed anything, then we can put those into a category of "other class" investments. These may include investment art objects, jewelry, gold coins, etc. held for future growth potential, but which are fairly non-liquid from one day to the next. Many advisors go further to specify many other "classes," but unless you are going to analyze your investments under a microscope, these four classes will go a long way toward helping you make some wise personal financial investment decisions.