Dividend yield
Dividend yield is often referred to simply as yield. It is the rate of return investors get from holding the share. It is calculated by taking the total dividends paid per share over the course of a year and dividing by the share price.
For example, if a share pays out 20p in dividends over the course of a year and trades at 500p, then it has a dividend yield of 4%.
The dividend yield usually means the historical dividend yield: the current price divided by the dividend declared in the last financial year. Forward looking numbers are used as well, but should be specifically identified as such.
Special dividends should be excluded when calculating the yield. So if the company in the example above had also paid a 100p special dividend during the year, its yield would still be 4%.
Mature, well-established companies tend to have higher dividend yields, while young, growth-oriented companies tend to have lower yield. Many fast growing companies do not have a dividend yield at all because they do not pay out dividends.
Simple financial theory suggests that dividends are irrelevant for valuation.