April Fools' Day is a traditional Western festival,which falls on the 1st of April.
It is similar to Ancient Rome's Hilaria and India's Holi.
Its choice of time and date seems related to Vernal Equinox (March 21).
During this period of time,the weather often changes abruptly,appearing like the nature is trying to hoax/fool the human beings.
There are numerous different opinions regarding the origin of April Fools' Day.