Support and resistance are very important ingredients in technical analysis.
Support is a price level at which a financial instrument (stock, bond, currency, futures contract, etc.) will likely stop falling and resistance is a level at which the price will likely stop rising.
Support and resistance are not exact. More than specific prices on a chart, support and resistance can be considered price bands or ranges where the price will probably stop falling or rising respectively. Nevertheless, due to their widespread use throughout the history of all financial markets, support and resistance frequently work. As a result, many traders use support and resistance as part of their strategies.
Support and resistance levels can apply to a short period of time in a chart (like days) or to a much longer time frame (months, or years). As a result, not all support or resistance levels are as strong and a day trader must take this into consideration when trading near support or resistance levels.