RAP charting, page-2224

@KoiPanda Say for example a share opens higher in the morning than it closed the night before then there is a Gap in the chart. For some inexplicable reason this gap is almost always closed, by the share price retacing backwards before going forward again. There are gaps that don't get closed such as runaway gaps.

This is just a simplistic answer, my suggestion to you would be to google Charting and Gaps and you will get a lot of information that will help you understand it more.