Though joke-lovers in many countries joyfully fool friends on April Fool's Day, no one knows exactly when or why, or even where, this tradition began.   Practical joking seems to have coincided with the coming of Spring since the time of Ancient Romans and Celts, Some trace  April Fool's Day back to Roman mythology , particularly the story of Ceres ,Goddess of the harvest, and her daughter, Proserpina. Pluto, God of the Dead, cheated Proserpina and took her to live with him in the underworld, The girl called out to her mother, but Ceres could only hear the echo  of her daughter's voice. Such 'fool's errands ' became a popular practical joke in Europe in later centuries.   The most widespread theory of the origin of April Fool's day the switch from the old Julian to the Gregorian calendar in the late 16thcentury. Under the Julian calendar, it was celebrated during the week between March 25 and April 1, but under the Gregorian calendar, it was moved to January1. Those who weren't informed of the change, or stubbornly kept to the old tradition, were often laughed at and had jokes played on them or around the old New Year.   In France, this took the form of practical joker sticking fish on the backs of those who celebrated the old custom, earning the victims of the joke the name Poisson d' April, or April Fish. In Scotland, the butts  of April Fool's jokes were known as April "Gowks", another name for a cuckoo bird.   In more recent times, radio stations, TV programs and Web sites have set up gullible readers and listeners. One of the most famous jokes was a 1957 BBC program of the annual spaghetti harvest in Switzerland. Were so fooled they wanted to find out how to get a spaghetti bush of their own. Many listeners So while you're surfing the web or watching TV today, be aware of what you see and read, or you should end up an April Fool ! The text is mainly to   _  .
explore the origin of April Fool' Day. warn readers against being cheated show versions of the origins of April Fool' Day. introduce the real tradition of April Fool's Day