CHRISTMAS celebrates the birth of Jesus Christ in Bethlehem.
For Christians, the holiday is an important time to attend church and reflect on the sacrifices made by Jesus.
What is midnight mass?
Midnight mass is a tradition that sees Christians gather for a service on Christmas Eve.
The service generally starts just before midnight and is a vigil seeing in the arrival of Christ's birth.
It includes a mass - also known as eucharist, communion, or breaking of bread - where believers share bread and wine in remembrance of his death.
It is believed the tradition started in the Western World from about 430AD under Pope Sixtus III in the Basilica of St Mary Major.
READ MORE ON CHRISTMAS
Midnight mass became widely popular by the twelfth century.
There are also services generally held at dawn, and during Christmas Day.
Why do people go to church on Christmas Eve?
The Roman Christian historian Sextus Julius Africanus dated Jesus' conception to March 25.
It is thought that December 25 was chosen as it is exactly nine months after this date.
MOST READ IN NEWS
The Bible does not specify Jesus' date of birth.
December 25 might also have been chosen because of the winter solstice – the shortest day of the year.
By attending midnight mass, Christians dedicate the festive season to God and celebrates Christ's birth.
Where are the most famous services?
For Catholics, the big Christmas Eve mass is traditionally celebrated at the Vatican.
People gather at St Peter's Basilica to hear the Pope's Christmas message.
It's so popular that people are advised to book no less than two months in advance.
One of the most famous landmarks in London for midnight mass is Westminster Abbey.
The First Eucharist of Christmas will be held at 11.30pm, but can only be attended by free ticket only.
The Midnight Eucharist will also be held at 11.30pm at St Paul's. The service will run until 1am.
For those looking to travel further abroad, midnight mass is also held in Bethlehem - widely believed to be the birthplace of Jesus.
While there are limited tickets, crowds also gather outside the church in Manger Square.
Notre Dame also hosts a midnight mass service, with bells pealing out to mark the occasion.
The services are generally held in French, but tourists can also appreciate the historical building's grandeur.
ncG1vNJzZmivp6x7tbTErKynZpOke7a3jqecsKtfbX11gJVqbGilmZm7qrPHrWSmmaOoeri02Gaaoa2imLVur8eroKysnZbAbrHVnmSfmZ2kwrR50p6pr6GTmsBw