#4sqDay Foursquare Day是一个全球性的社会化媒体节日。它由地理位置社会化媒体Foursquare的用户（俗称“四方党人”）于2010年起自发组织的非盈利活动，并得到了Foursquare官方的支持。因为Foursquare可以理解为4的平方（16），所以Foursquare Day的首创者们把每年的4月16日定为Foursquare Day。
上海是中国唯一一个与全球同步举行过2010年、2011年两次Foursquare Day的城市。2010年4月16日，上海的一批四方党人在4sqDay Shanghai聚会后获得了Swarm Badge（50+用户同时check in），2011年4月16日，4sqDay Shanghai得到了静安希尔顿酒店及美团网等的赞助在静安希尔顿酒店举行，很多四方党人获得了Super Swarm Badge（250+用户同时check in）。
今年，4sqDay Shanghai得到了上海商城、三星Galaxy Note、第九城市飞空冒险王、上海波特曼丽嘉酒店等赞助商的支持，得以在上海商城举办。今年活动的终极目标是吸引到500名四方党人参加check in，以期帮助每一位四方党人获得Super Duper Swarm Badge。得益于各赞助商的大力支持，与去年一样，今年的4sqDay Shanghai仍将是一个免费参加的活动，您只需要在现场使用Foursquare App在上海商城check in就能入场参加活动。活动现场还将向所有参加活动的四方党人免费提供酒水饮料。
为了使今年的4sqDay Shanghai更有意义，我们首次引入了公益元素。参与活动的四方党人可以以每张人民币20元的价格换取抽奖券以获得赢取三星Galaxy Note、苹果iPad 2等丰厚奖品。所有抽奖券收入将悉数捐赠给一家国际性公益机构。
需要说明的是，4sqDay Shanghai的组织团队全部由热心的Foursquare用户志愿参加，所有成员都未通过本次活动盈利。
Foursquare Day, a global social media event, was started in 2010 by the users of the location based social medium Foursquare, as a non-profit activity supported by the Foursquare headquarters. According to its namesake, Foursquare, the date is the square of the number four, thus Foursquare Day is celebrated every year on April 16th.
Shanghai is the only city in China that has hosted Foursquare Day alongside the rest of the world twice, both in 2010 and 2011. On April 16th, 2010, some members of the Shanghai Foursquare community won the Swarm Badge (a prize for more than 50 users checking in simultaneously) after 4sqDay Shanghai celebration. Supported by Hilton Shanghai and Meituan, 4sqDay Shanghai celebration was hold in the Hilton Hotel on April 16th, 2011. On that day, many users obtained the Super Swarm Badge (prize for more than 250 users check in at the same time).
This year, 4sqDay Shanghai is supported by more sponsors, namely Shanghai Centre, Samsung Galaxy Note, Fly King the 9 and the Portman Ritz-Carlton celebrating altogether at Shanghai Centre. The ultimate goal of this year festival is to attract 500 more users to check in, which will benefit every Foursquare user with the Super Duper Swarm Badge. Boosted by strong support from all the sponsors, 4sqDay Shanghai of this year is again a free-entry activity just as last year. Only to use the Foursquare App at Shanghai Centre to check in and you will be invited to the celebration. All the attendees will be served free beverages.
To make the theme of 4sqDay Shanghai this year more significant, we have introduced charity to the celebration. Attendees can buy a raffle ticket for 20RMB to win great prizes such as a Samsung Galaxy Note, iPad 2 and so on. All revenue will all be donated to an international charity. And of course, volunteers organizing 4sqDay Shanghai will never get any profit from this activity.