(CNN) -- Here's a look at what you need to know about Easter and Holy Week.
On Easter Sunday, Christians celebrate the resurrection of Jesus Christ on the third day after his crucifixion. It also marks the end of the 40-day period of penance called Lent. Easter is considered to be the most important season of the Christian year.
Easter: April 20, 2014 - Easter Sunday
It is celebrated on the first Sunday after the first full moon following the first day of spring.
In some countries, Easter is called "Pascha", which comes from the Hebrew word for Passover.
The Jewish holiday of Passover took place just before Christ's crucifixion and resurrection.
The Eastern Orthodox Church uses other factors to determine the date and will celebrate this year on May 5.
Christianity is one of the world's largest religions, with approximately two billion followers around the world.
Palm Sunday April 13, 2014 - Palm Sunday
For Christians, Palm Sunday commemorates Jesus' arrival in Jerusalem prior to his crucifixion, where palm leaves and clothing were laid in his path.
Palm Sunday is often celebrated with a procession and distribution of palm leaves.
In some churches, the palms are saved and burnt into ashes to be used on Ash Wednesday of the next year.
Palm Sunday is also called Passion Sunday.
It is the last Sunday of Lent and first day of Holy Week.
Maundy Thursday April 17, 2014 - Maundy Thursday, also called Holy Thursday.
The observance commemorates the Last Supper, before Jesus' crucifixion.
Some churches hold a special communion service.
Good Friday April 18, 2014 - Good Friday.
For Christians, it is a day of mourning and penance. Good Friday marks the day Jesus died on the cross.
Good Friday is celebrated the Friday before Easter Sunday.
Many observe the day by fasting and attending church services.
Celebrated since 100 AD as a day of fasting, Good Friday acquired significance as a Christian holy day in the late fourth century.
Symbols & Customs: Eggs have long been a symbol of life and rebirth.
Painting and dying eggs pre-dates Christianity.
Polish folklore has the Virgin Mary offering eggs to the soldiers guarding Christ on the cross, as she begged them to be merciful, her tears left stains on the eggs.
1885 - The Czar of Russia commissions the jeweler Faberge to design an enameled egg each Easter.
The first Faberge egg contained a diamond miniature of the crown and a tiny ruby egg.
Of the 50 Imperial Easter Eggs made, most are now in museums.
Origins of the Easter Bunny are unclear, but he appears in early German writings.
The first edible Easter bunnies appeared in Germany in the 1800s, and were made out of sugar and pastry.
Jelly beans first became part of Easter celebrations in the 1930s.
Commercialization of Easter: 2013 - The average shopper is expected to spend $145.13 for Easter on everything from candy to clothes, about the same as last year's average of $145.08. Total spending on Easter is expected to reach $17.2 billion.
More than 16 billion jelly beans are made in the U.S. for Easter each year.
Around 90 million chocolate bunnies are made for Easter each year.