An inside range day is one in which that days range is completely inside of the last days price range. Breakouts from inside ranges, especially in the direction the prevailing trend make great buys. The reason behind this is that an inside range day represents the sellers becoming less confident in the continued decline of a stock. Many times when a stock breaks out from IRD's you get a day in which the open is the low, and the close is the high. A narrow range day is one in which the range of the day is smaller than the average range, this is generally a judgement call.
Markets exist in three distinct faces.
The second face markets exist in is trending . I tend to focus on as trends are very easy to identify, and do not easily change. The final faze markets exist in is distribution . This is where the smart money is getting out and the dumb money is getting in. We try and avoid this area of market activity as well.