The first Easter was celebrated in Babylon, 4400 years ago, around 2400 BC. The Zoroastrians celebrated a holiday called "No Ruz" which was Spring Equinox festival held in late March, early April. Just like the Zoroastrians there were other religions that celebrated similar Spring Equinox celebration, some even have the death and rebirth of their gods, like the Greeks and Egyptians in honor of their Gods Dionysus (of the Greeks) and Osiris (of the Egyptians).
Eostre is the ancient Anglo-Saxon goddess of fertility. She mated with the sun god at the first full moon after the Equinox and after 9 months labor she gave birth during the Winter Solstice.
Two of Eostre's symbols were the hare and the egg (which symbolized rebirth). This is the first time a Bunny is mentioned in Easter.
The first Christian Easter was celebrated in 325 A.D. by the Church Council of Nicaea, who felt this should be celebrated just as much as any other holiday.
The Equinox and Easter are very close and many Catholics habitually see this holiday as Christ's resurrection from the dead on Good Friday. They see this day as being synonymous with rebirth and rejuvenation of the plant and animal life.
Some of ancient pagan religions are mixed into the traditional stories because of the early Christian missionaries. They used existing holidays and point out similarities to the people they were trying to convert. The purpose changed over time, but some of the old customs and traditions would remain. Such a custom was the Easter Hare, generally known today as the Easter Bunny.
Easter is "Pachons" in Latin, "Pascha" in Greek, "Pessach" in Hebrewand and "Pa-Khonsu" in Egyptian, "Khonsu" being a nickname for the sun god Horus. In Anglo-Saxon, Eostre is goddess of the dawn, corresponding to Ishtar, Astarte, Astoreth and Isis. The word "Easter" shares the same root with "east" and "eastern," the direction of the rising sun.
The Spring Equinox usually falls somewhere between March 19th and 22nd and depending upon when the first full moon after the Equinox occurs, Easter falls sometime between late-March and mid-April.