Support & resistance are simple concepts, just like trend, but with the highest importance in technical analysis. 

Support: An area in a chart where buyers are stronger than sellers. As a consequence when in a downtrend price visits this area, it reverses upwards or stops temporarily from declining. It is depicted by a horizontal line which joins two or more candlestick lows although we can define support by using only one point. In that case we infer the existence of support by the upward movement of prices.

Two or more points support: Support at $19.25.

 

One point support

 

Resistance: It is in a way the opposite of support meaning an area in a chart where sellers are stronger than buyers. As a consequence when in a uptrend price visits this area, it reverses downwards or stops temporarily from rising. It is depicted by a horizontal line which joins two or more candlestick highs although we can define resistance (just like support) by using only one point. In that case we infer the existence of resistance by the downward movement of prices.

Two or more points resistance: Resistance at $25.20.

 

One point resistance

 

Instead of having just one price which is support or resistance, most of the times we have support/resistance zones.

Support zone between $134.40-$135.90

 

Resistance zone between $141.66-$142.21