In general, a reading above 1.00 is bearish and a reading below 1.00 is bullish. If it's sitting at 1.00, it's a neutral reading. TRIN is used to give Trader's an idea as to the sentiment in the market.
The chart below shows a 5 day chart of TRIN. Note the whipsaw action that takes place.
Related terms: Market Breadth, Bollinger Bands, Parabolic SAR, Target, Technical Analysis