Retracements are temporary reversals of a stock’s direction, which is often referred to a correction that occurs during a lasting trend. For instance, in an upward trend, it is a dip in the stock price, until it continues in the previous upward trending direction.
Support is a low-price range, where buying activity is enough to stop declines in prices.
Resistance stops rise in prices. This lends itself to the change in the polarity principle, where once a support level is breached, it becomes a resistance level.