A double top is two attempts at the same high that both fail, separated by a pullback. A double bottom is the same thing at a low. They are the most common reversal shapes you will see, and also the most commonly traded too early.
Reading the double top
Price rises to a high, pulls back to a trough, rises again to roughly the same high, and fails again. The trough between the two peaks is the neckline. A close below it completes the pattern.
The peaks do not need to be identical. What matters is that buyers tried twice at essentially the same price and got rejected twice. If the second peak is meaningfully higher, you do not have a double top — you have an uptrend.
Reading the double bottom
Exactly mirrored: two lows at a similar level, a bounce between them, and a breakout above that bounce high. Sellers failed twice at the same price; the buyers only need to clear the midline.
Why these fail so often
Here is the uncomfortable part. In a strong trend, a double top is frequently just a pause — price pulls back, chops, and continues up. The pattern only has real meaning when the preceding trend is already showing signs of exhaustion: slowing momentum, smaller advances, longer pullbacks.
Without that context you are trading a shape in a vacuum, and the base rate is poor.
Doubles versus triples
A third test of the same level gives you a triple top or bottom. It is the same idea with one more failure. Slightly more reliable in principle — three rejections beat two — but rarer, and by the third test a lot of traders are already positioned, which can make the eventual break violently fast in either direction.
How to check this yourself
Mark twenty double tops on historical charts — and here is the key part — also mark how many of them occurred in a clear uptrend versus after the trend had already flattened. Compare what happened next in each group. That comparison will teach you more about context than any rule about peak spacing.