Seasonality
Seasonality is a tendency for an asset to move in a similar way in the same calendar month or season year after year.
Crypto folklore has names for it, such as Uptober, Moonvember and the Santa rally. Whether it is real is a statistics question: each calendar month has only a handful of years of data, and the coins move together, so the sample is small.
See how each month has actually gone in our seasonality by month pages, which state how many years stand behind every figure.