People around the world are wearing colorful or striking mismatched socks to raise awareness for World Down Syndrome Day.

Since 2013, the tradition has been practiced on March 21 to show support for people with Down syndrome and spark conversation with people who don’t know about the awareness day.

How did socks become a World Down Syndrome Day tradition? 

Well, organizers at Down Syndrome International first introduced the idea of wearing flashy socks on World Down Syndrome Day in 2013 with an "odd socks" theme.

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Socks were selected as the theme because it’s an easy way for people to get involved.

"We encourage our supporters to wear their most eye-catching socks to start conversations," a spokesperson for World Down Syndrome Day told Fox News Digital.

Wearing fun socks gives the wearer an opportunity to let any inquirers know that they’re wearing their socks to raise awareness for Down syndrome.

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Colorful mismatched socks

People around the world are wearing colorful or striking mismatched socks to raise awareness for World Down Syndrome Day, which is observed on March 21 each year. (iStock)

Over time, the sock-wearing tradition has evolved into larger social media campaigns that the world might be more familiar with today, including "#LotsOfSocks" and "#RockYourSocks."

Some World Down Syndrome Day observers have noticed that sock-like shapes have a similar appearance to chromosomes. 

This observation has even led some to believe that wearing noticeable socks on World Down Syndrome Day is a symbolic way to represent the extra chromosome that causes Down syndrome.

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Down Syndrome International has not made the same chromosome connection, however.

World Down Syndrome Day got its start in 2006 and was originally a campaign that intended to generate international support, according to a timeline shared by Down Syndrome International.

On Dec. 19, 2011, the United Nations General Assembly officially declared March 21 to be World Down Syndrome Day. 

A press release detailing the historic resolution stated that 191 countries would participate in the first UN-recognized World Down Syndrome Day on March 21, 2012.

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"The date for WDSD being the 21st day of the 3rd month, was selected to signify the uniqueness of the triplication (trisomy) of the 21st chromosome which causes Down syndrome," says an excerpt from the World Down Syndrome Day website.

The UN estimates that 3,000 to 5,000 babies are born with Down syndrome each year worldwide.  

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Besides socks, other activities are done on World Down Syndrome Day, too. 

Observers often choose to donate funds to a charity or awareness group that focuses on bettering the lives of people with Down syndrome. Or as a free alternative, people choose to perform challenges that involve the number 21, which could mean walking or running 21 miles or doing 21 push-ups.

Down Syndrome International and the UN are encouraging World Down Syndrome Day observers to think about inclusion means in 2022.

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"The United Nations Convention on the Rights of Persons with Disabilities (UN CRPD) calls for ‘Full and effective participation and inclusion in society,’" World Down Syndrome Day’s spokesperson told Fox News Digital. "But in reality, people with Down syndrome and disabilities do not benefit from full inclusion."

"We believe that this is due to a lack of understanding of what inclusion is," they continued. "So tell, us ‘Inclusion means...’"