It's the start of Veganuary where many people try to eat a plant-based diet all of the month of January.
The month was created in 2014 by a couple in America to encourage people to try out veganism, learn more about the lifestyle and movement.
But what is a vegan?
A vegan is someone who does not eat or use animal products.
Unlike a vegetarian diet - where people don't eat meat or fish - a vegan diet avoids all animal products like dairy, eggs and even honey as well as meat and fish.
Some people prefer to call this way of eating 'a plant-based diet'.
Following a vegan lifestyle also means only using or buying cosmetics and clothes free from animal products.
Research by the Vegan Society found the number of vegans in Great Britain increased from 150,000 in 2006 to 540,000 in 2016.
Many believe the number of people who call themselves vegans could now be in the millions.
Many celebrities, including Ariana Grande, Miley Cyrus and tennis ace Venus Williams are vegans, and they've talked publicly about it raising awareness.
There's also been a big rise in vegan cafes and restaurants meaning there's much more choice.
In June 2019, fast food chain KFC introduced their first vegan burger in the UK - made up of vegan Quorn fillet coated in the Colonel's secret recipe, lettuce and vegan mayo.
The animal rights group Peta called it "game-changing" and said that they "we're confident it will be a huge hit with the skyrocketing numbers of vegans, vegetarians, and flexitarians around the UK."
The 2018 series of The Great British Bake Off introduced a 'vegan week' to add to the regular challenges such as 'bread week'.
Bake Off judge Paul Hollywood told the BBC: "Veganism seems to be growing and we wanted to represent that."
There are many reasons people decide to go vegan. They include:
1. Animal Cruelty
Some people become vegan because they love animals and they think harming any animal is cruel.
For vegans, it's not just about animals which are killed for food, but also concerns about the way that cows and chickens used for dairy and eggs are treated, especially in big factory farms.
The United Nations says that farmed livestock accounts for 14.5% of all manmade greenhouse gas emissions.
This is roughly equivalent to the exhaust emissions of every car, train, ship and aircraft on the planet.
Just one cow gives off enough harmful methane gas in a single day to fill around 400 litre bottles, which is really bad for the environment.
Another argument used for veganism is that meat and dairy production uses too much land.
Some vegans say they stopped eating meat for health reasons, but some people worry about getting the right vitamins and minerals from a vegan diet.
The British Dietetic Association, which represents experts in nutrition, says that a "balanced vegan diet can be enjoyed by children and adults".
However, it also says it is important to plan meals to make sure that it includes enough nutrients.
Would you ever try being a vegan? Or do you think it is not for you? Let us know in the comments.