A Gap is a change in price levels between the close and open of two consecutive days. For trading purposes, the four basic types of gaps are as follows:
Full Gap Down occurs when the opening price is less than yesterday's low
Full Gap Up occurs when the opening price is greater than yesterday's high price.
Partial Gap Up occurs when today's opening price is higher than yesterday's close, but not higher than yesterday's high.
Partial Gap Down occurs when the opening price is below yesterday's close, but not below yesterday's low.
