Look at the diagram above. As you can see, this zigzag pattern is making its way up (bull market). When the market moves up and then pulls back, the highest point reached before it pulled back is now resistance.
As the market continues up again, the lowest point reached before it started back is now support. In this way resistance and support are continually formed as the market oscillates over time. The reverse is true for the downtrend.
Plotting Support and Resistance
One thing to remember is that support and resistance levels are not exact numbers.
Often times you will see a support or resistance level that appears broken, but soon after find out that the market was just testing it. With candlestick charts, these “tests” of support and resistance are usually represented by the candlestick shadows.