This picture is the image of Google search engine in China on August 13, 2013. Yes, today is Chinese Valentine's Day! It is not celebrated every August 13, but it is celebrated every 7th day of 7th month of Chinese lunar calendar.
There is a romantic story behind this festival: One day a daughter of The Jade Emperor went to visit the earth. He met a shepherd and both of them fell in love. When the father found out about this, he was so angry and asked the daughter to go back to heaven. The daughter was very sad. Because of this, the father finally allowed the couple to meet once a year, every seventh day of the seventh month of lunar year.