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dividend yield
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hart's answer regarding the difference between an index and a stock aside, remember that dividend yield is a passive measure.  it takes the announced dividend (which is a $/share amount) and divides it by the current market price.   so you can't assume that if you buy a stock that had a dividend yield of 4% for $100 that you're guaranteed 4% of the stock price in dividends.  if the price of the stock doubles, you'd still get $4, but the yield would drop to 2%.  or the company could reduce (or even suspend) its dividends, which would reduce the yield if the stock price stayed flat. for an index like the s&p, it's easier to measure dividends on % yield terms rather then $/share terms since you'd have to own shares in every single company to get that amount, but on average the stocks in the s&p 500 pay x% in dividends (which are typically quarterly) - some pay more than that, some less, and some none at all.
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