In a chart, a gap represents an area where no trading takes place. It is essentially an empty space between one trading period and the previous.
The GAP is formed when there is a large-enough difference in the opening price of a trading period where that price and the subsequent price moves do not fall within the range of the previous trading period.GAP named based on their place of occurrence. There are The four types of GAP are Area Gap or Consolidation, Break out GAP, Runaway GAP, Exhaustion GAP. The GAP appear in charts because of an overnight speculations, breaking news, etc., So, if something happens to cause a GAP then it denotes a massive movement in market and it makes the price to volatile.