Here we have St. Nicholas, a Bishop who lived in the fourth century in a place called Myra in Asia Minor (now called Turkey). He was a very rich man because his parents died when he was young and left him a lot of money. He was also a very kind man and had a reputation for helping the poor and giving secret gifts to people who needed it. Because of his kindness Nicholas was made a Saint. Nicholas was exiled from Myra and later put in prison during the persecution by the Emperor Diocletian. No one is really knows when he died, but it was on 6th December in either 345 or 352. In 1087, his bones were stolen from Turkey by some Italian merchant sailors. The bones are now kept in the Church named after him in the Italian port of Bari. On St. Nicholas feast day (6th December), the sailors of Bari still carry his statue from the Cathedral out to sea, so that he can bless the waters and give them safe voyages throughout the year.
So, How did St. Nicholas become Santa Claus??
In the 16th Century in northern Europe, after the reformation, the stories and traditions about St. Nicholas became unpopular.
But someone had to deliver presents to children at Christmas, so in the UK, particularly in England, he became 'Father Christmas' or 'Old Man Christmas', an old character from plays during the middle ages in the UK and parts of northern Europe. In France, he was then known as 'Père Nöel' in Germany, the 'Christ Kind'. In the early USA his name was 'Kris Kringle'. Later, Dutch settlers in the USA took the old stories of St. Nicholas with them and Kris Kringle became 'Sinterklaas' or as we now say 'Santa Claus'!
Many countries, especially ones in Europe, celebrate St. Nicholas' Day on 6th December. In Holland and some other European Countries, children leave clogs or shoes out on the 5th December (St. Nicholas Eve) to be filled with presents. They also believe that if they leave some hay and carrots in their shoes for Sinterklaas's horse, they will be left some sweets.
St. Nicholas became popular again in the Victorian era when writers, poets and artists rediscovered the old stories.