He's refering to Stochastics, MACD, RSI, as indicies. when their valuse are in the top part of their range they are overbought, for instance Stochastics, fi the show their lines are up in the 80 area that tells you the stock is overbought. If their lines are in the 20 area towards the bottom of their range that says the stock is over sold. HOWEVER, when a stock gets into a strong run one way or the other their values can remain in one range for an extended period of time.
You can learn about indicies and how to use them at stockcharts. they have free charts and good learning tools to help you become familiar with them.
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