Seasonality captures effects that occur with specific frequency. It can be driven by many factors.
Short-term regular wave-like patterns
Observed within 1 year
Often monthly or quarterly
Naturally occurring events, such as weather fluctuations caused by time of year
Business or administrative procedures, such as start and end of a school year
Social or cultural behavior, such as holidays or religious observances
Fluctuations due to calendar events, such as the number of Mondays per month for trading or holidays that shift from year to year (Easter, Chinese New Year)