But what about all the Gregorians? Well, here's how the parties differ:
The biggest party is in Sydney, with two million people gathering for a fabulous fireworks display set to music over the Sydney Opera House and Sydney Harbour Bridge.
The celebration is then broadcast on televisions across the world, to show everyone the kind of thing that they themselves can soon expect.
AustriaAustrians call New Year's Eve Sylverterabend, after Saint Sylvester. Sylvester was a Pope in the 300s, and was buried on December 31st.
German-speaking countries and some others close-by recognise the 31st as the feast of Sylvester. In Austria, there are public concerts and lots of spiced punch (called Punsch) and mulled wine (called Glühwein), which are sold from the market stalls.
BelgiumThe Belgian New Year's Eve is called Sint Sylvester Vooranvond or Saint Sylvester Eve. It's pretty standard fare: Everyone eats, drinks, parties, and kisses at midnight. The party is called the Réveillon.
New Year's Day is called Nieuwjaarsdag, and children read wishes that they have written on cards, and give and drawings to their parents. Apparently, Belgian farmers always wish each of their animals a Happy New Year. I don't know about kissing them!
Two million partygoers head to the Copacabana beach in Rio for the carnival, and thousands of candles are lit and washed out to sea.
People drink a lot, and there is a tradition called 'first footing' where the first person over the threshold of a house after midnight must bring coal, bread, milk, alcohol... For luck. The gifts are then distributed to all the people in the house.
There are also New Year's Resolutions which involve people deciding to give something up for a whole year, such as smoking. Recently, resolutions have involved starting something new as well - such as going to the gym. The most important thing about New Year's Eve is unfortunately the drinking, though.
A ship shape means a journey and a pig shape equals food. So there you go. And they leave a bit of each food on the table, to ensure they have enough to eat for the year ahead. But what happens to that food? Don't you think it goes in the bin on New Year's Day?
The traditional food is the Vassilopitta cake, and anyone who finds a silver or gold coin inside it will be lucky for the whole year
This is because the tradition in Hungary on the 31st December is to burn an effigy called Jack Straw - which represents all the evil and bad luck in the world. The effigy is taken around all the villages.
Families give money to children in a tradition called otoshi-dama (New Year treasure), and houses are decorated with origami cranes which, along with the turtle, are thought to bring peace and happiness.
In South Korea, many people travel to Jung dong jin on the peninsula, for the first view of the sun.
PhilippinesNew Year is great in the Philippines, especially if you are a child. It is believed that children who jump about will grow taller in the coming year, and many children rattle tins containing coins to bring wealth to the people.
Many people wear clothes with dots on them, as this symbolizes health and fertility. Similarly, tables are decorated with baskets of twelve different round fruits, to symbolize prosperity in each coming month.
Portugal and Spain
This usually takes place at the family party, and then the young people go to discos, and aren't seen again until February.
Generally, the Scots have a huge party in Prince's Street in Edinburgh, during which everyone holds hands, sings, and gets very very drunk. And there might be some sword-dancing, too!
In the South, the more rustic way of celebrating New Year is to eat black-eyed peas, 365 if possible, along with a lot of peas or turnips - which all signify green American money for the coming year.