Christians celebrate Easter to commemorate the resurrection of Jesus Christ. Some aspects of modern Easter celebrations, however, pre-date Christianity.
According to the Venerable Bede, Easter derives its name from Eostre, an Anglo-Saxon goddess of spring. A month corresponding to April had been named "Eostremonat," or Eostre's month, leading to "Easter" becoming applied to the Christian holiday that usually took place within it. Prior to that, the holiday had been called Pasch (Passover), which remains its name in most non-English languages.
In Medieval Europe, eggs were forbidden during Lent. Eggs laid during that time were often boiled or otherwise preserved. Eggs were thus a mainstay of Easter meals, and a prized Easter gift for children and servants.
In addition, eggs have been viewed as symbols of new life and fertility through the ages. It is believed that for this reason many ancient cultures, including the Ancient Egyptians, Persians, and Romans, used eggs during their spring festivals.
Many traditions and practices have formed around Easter eggs. The coloring of eggs is a established art, and eggs are often dyed, painted, and otherwise decorated. Eggs were also used in various holiday games: parents would hide eggs for children to find, and children would roll eggs down hills. These practices live on in Easter egg hunts and egg rolls. The most famous egg roll takes place on the White House lawn every year.
Hares and rabbits have long been symbols of fertility. The inclusion of the hare into Easter customs appears to have originated in Germany, where tales were told of an "Easter hare" who laid eggs for children to find. German immigrants to America -- particularly Pennsylvania -- brought the tradition with them and spread it to a wider public. They also baked cakes for Easter in the shape of hares, and may have pioneered the practice of making chocolate bunnies and eggs.