Gaps are much easier and more clearly explained on Technical Analysis boards, of which both Stock Analyzer and Stock Lobster are excellent at. Penny TA does a great job, too. There are a whole host of others here on IHub, who are unbiased, as well.
However, some TAs will 'slant' things to their own benefit, with 'power of suggestion', using TA as their basis.
IMO, as much as TA is a valuable tool, it is not always perfect, since obviously, it does not go by fundamentals, and cannot read PR.
Also, in regards to gaps, not ALL gaps MUST be filled. It is documented that a full 70% of all TRUE trend reversal gaps go unfilled, if 'follow thru' volume continues in the reversal. This generally only happens when a stock has bottomed for a period of time, and then hits the market with a substantial fundamentally progressive PR.