Head and Shoulders
A three-peak shape where the middle peak is the highest and the two outer peaks are roughly level. The line drawn under the two troughs is the neckline, and the pattern is said to complete when price closes below it.
The best known reversal shape in technical analysis, and the one most often seen where it is not. Three peaks occur constantly in any noisy series; what the detector requires is that the middle peak clears both shoulders by a margin larger than the recent average range, that the shoulders sit at a similar height, and that a real trend preceded the formation — without a prior advance there is nothing for it to reverse. The measured record below is for completed occurrences only, meaning price actually closed through the neckline; a shape that never breaks is not a signal, and counting it as one is how success rates get inflated.