Small Business Saturday is an American shopping holiday held on the Saturday after Thanksgiving during one of the busiest shopping periods of the year. First observed on November 27, 2010, it is a counterpart to Black Friday and Cyber Monday, which feature big box retail and e-commerce stores respectively. By contrast, Small Business Saturday encourages holiday shoppers to patronize brick and mortar businesses that are small and local. 

In 2010 the holiday was conceived and promoted by American Express via a nationwide radio and television advertising campaign. That year Amex bought advertising inventory on Facebook, which it in turn gave to its small merchant account holders,^[1] and also gave rebates to new customers to promote the event.^[2][3]

American Express publicized the initiative using social media, advertising, and public relations. At least 41 [1] local politicians and many small business groups in the United States issued proclamations concerning the campaign,^[4][5][6] which generated more than one million Facebook "like" registrations and nearly 30,000 tweets under the Twitter hashtags #smallbusinesssaturday (which had existed since early 2010) and #smallbizsaturday.[2]

The Twitter hashtag #SmallBusinessSaturday has existed since early 2010 and was used to promote small businesses on any Saturday (not solely that Saturday between Black Friday and Cyber Monday). The hashtag is used in a manner similar to #FollowFriday to highlight favorite local businesses.

Description thanks to Wikipedia.