We believe a trader is better off recognizing the environment she is in by seeing the overall pattern of highs and lows and gauging the momentum before making the decision to go with a trending strategy in which once she is in the trade, she may use a lagging indicator and plan to allow the trend to develop. Or a trader can decide to employ a counter trend strategy in which he uses support and resistance, individual candle behavior, and/or a leading indicator to get in and out of trades faster.
A very important difference between a trending market and a counter-trend market is that in the first one the higher time frames will dictate price movement and direction, whereas in a counter trend environment the lower stage frame charts can dictate direction. This means that in a trending market you do not want to go against the trend on the next higher time frame. In a countertrend market you are taking signals on the lower time frames routinely regardless of the previous direction on the higher time frames.
The importance of trending and the counter trends is because to be a complete trader, you must do both. You can even choose what to master trending or counter trends, it's not necessary to do both.
The easiest way to define whether you are in a trending or a counter trending market is to define the trends on the different time frames and see if they are in agreement, which would mean a trending market, or are conflicting, which would mean a counter trend market.