A double top is a reversal pattern that is formed after there is an extended move up. The “tops” are peaks which are formed when the price hits a certain level that can’t be broken. After hitting this level, the price will bounce off it slightly, but then return back to test the level again. If the price bounces off of that level again, then you have a DOUBLE top!
Two peaks or “tops” were formed after a strong move up. Notice how the 2nd top was not able to break the high of the 1st top. This is a strong sign that a reversal is going to occur because it is telling us that the buying pressure is just about finished.