People celebrate New Year in a number of ways.
On 31st December, the festivities hit places around the world at slightly different times too, due to the time differences across the world.
Check out the video below to find out how it works.
Some cultures may celebrate New Year at a different time to 31st December, because they use a different calendar to the UK.
Generally, whenever they take place, New Year traditions are designed to bring luck and good fortune in the year ahead.
Find out below how people may be celebrating the start of 2017 all over the world.
Big fireworks displays
One of the most popular ways to celebrate seeing in the New Year is with big fireworks displays.
These take place all over the world, as different countries hit midnight.
In New Zealand, crowds gather at Auckland Sky Tower in the capital for an impressive fireworks display, and the same happens in Sydney Harbour in Australia.
In Toronto in Canada, people gather in Nathan Phillips Square, while in Rio de Janeiro in Brazil, people flock to the city's famous Copacabana beach to watch the sky being lit up by fireworks.
If you came out of your front door to find a load of smashed plates, you might be a bit confused.
But that's exactly what people in Denmark hope to find after midnight, as it means good luck.
So, if you were Danish, you might go and smash a plate on a friend's doorstep to bring good luck over the next 12 months.
In Brazil, there is a tradition to eat lentils at New Year, as these represent money - meaning good fortune for the year ahead!
In New York in the US, huge crowds of people head to Times Square to count down to midnight.
But the thing that everyone is looking forward to is called the ball drop, which is when a glowing ball is lowered down a big flagpole, to signal the start of the new year.
As a result, other cities in the US now have their own traditions of dropping things on New Year's Eve.
In Vincennes in Indiana, people drop watermelons from high up!
Visiting friends first
In Scotland, people go "first-footing", which is where they aim to be the first person to step foot in their friends' or family's homes after the clock has struck midnight.
You might take a gift if you go to do this.
Fortune telling with metal
Don't try this at home yourself!
In some countries including Finland, there is a tradition of melting a special metal and dropping it in cold water. The metal will make a shape in the water when it cools.
People then try to read the shape of the metal to tell them something about their future.
For example, if it makes the shape of a flower, it could mean they have an unknown admirer.
When the clocks hit midnight in Spain, you'll find people reaching for grapes.
This is because there is a tradition to eat one grape each time the clock strikes at midnight.
The idea is that this will bring you 12 lucky months in the year ahead.
Dressing up as bears
In Romania, there's a tradition for people to dress up as dancing bears to chase away any evil spirits.
This is because bears are special according to old Romanian stories and are able to protect and heal people.
Some countries, like Japan and South Korea, ring bells to start the New Year.
In Japan, the bells are rung 108 times, so you can expect it to be quite noisy!
In Johannesburg in South Africa, people like to start the year without any unwanted items.
They do this by throwing old furniture out of the window.
Walking an empty suitcase - yes, really!
In some South American countries, you might see some people on New Year's Eve walking around with an empty suitcase.
Some believe that taking what is called a "suitcase walk" means they will have a year full of adventures ahead.