TOMS Shoes is best known for their uniquely charitable "one for one" sales model; based on this model the company donates one pair of shoes to a needy child for each pair of shoes it sells. Now TOMS is making an even greater impact by leveraging the Instagram platform.

Between now and May 21, 2015, TOMS will donate a pair of shoes to a child in need for each Instagram photo of a pair of bare feet with the hashtag #withoutshoes. In other words, you can effectively prompt the company to donate a pair without making a purchase, so no matter how over the hashtag you are, this is a perfect opportunity to use one.

The TOMS One Day Without Shoes campaign is an ongoing effort to raise awareness about podoconiosis, a painful swelling disease which affects shoeless people. The idea behind the campaign is to show people how it feels to be without shoes for an entire day. This latest campaign is the eighth version of the original idea and may prompt the company to donate up to one million pairs of shoes to the people who most need them. Non-governmental organizations like Save the Children and UNICEF will coordinate the donations to ensure the shoes reach the right recipients.

To date, over the course of the One Day Without Shoes campaign, the company has donated 35 million pairs of shoes. This long history of charitable acts is part of the larger TOMS mission to shoe those with bare feet around the world.

"This isn't just about advocacy and giving based on your buying" TOMS Founder, Blake Mycoskie says. "It's about real giving for giving's sake. About 40% of the shoes we give away are made in the countries where we're doing the donating."

The TOMS "one for one" e-commerce policy has prompted other retailers to create similar social aspects in their business models.

Mycoskie founded TOMS Shoes in 2006 after getting hooked on the canvas shoes he found in Argentina shortly after he finished his appearance on "The Amazing Race." He got the idea to help others as he started his business, adapting the shoes for the American market. Since that time TOMS has also introduced coffee, eyewear, and just this past year, bags. Expanding the existing "one for one" policy, TOMS ensures that mothers and children in places like Guatemala, whose traditional textiles inspire many of the TOMS bag designs, receive materials for healthful childbirth.

The footwear industry has historically been home to high profit margins; TOMS uses this cushion to donate while staying in business. The strategy for doing well while doing good is working. In 2014 half of TOMS was purchased by investment firm Bain Capital. At that time TOMS was valued at about $625 million.

Mycoskie indicates that this capital is going to make aggressive expansion into South Korea, the Middle East, and Canada possible. These are carefully chosen regions "where people have a particular interest in being both fashionable and charitable."

So why Instagram?

"By leveraging Instagram, we can really make this a participatory event globally. To scale something like this in order to help more people is an incredible opportunity, and one that couldn't have happened just a few years ago. Social media is what makes TOMS possible. Spreading the word between people who care is so easy now."