case this is not so, for instance, if the support level comes down to the previous trough, it may signify that the uptrend is coming to the end or at least it is turning into a sideways trend. It is likely that trend reversal from up to down will occur. The opposite situation takes place in a downtrend; the failure of each support level to move lower than the previous trough may again signal changes in the existing trend.
In order to develop a support and resistance strategy you should be well aware of how the trend is identified through these horizontal levels. Thus, for an uptrend to go on, each successive support level should be higher than the previous one, and each successive resistance level should be higher than the one preceding it.
The concept behind support and resistance trading is still the same - buying a security when we expect it to increase in price and sell when expecting its price to go down. Thus, when the price falls to the support level, traders decide to buy creating demand and driving the price up. In the same way, when the price rises to a resistance level, traders decide to sell, creating a downward pressure and driving the price down