Michael Zhang (in blue robe), who is also known as Dr Tea, brews up a sample for a passer-by on World Tea Day at Harvard Square in Cambridge, MA, on April 16. The event has been held for eight years in China to celebrate the great tea tradition, also in France and India. Zhang said that serving free tea to a passer-by as an gesture to warm people up is a Chinese tradition dating back to the Tang Dynasty (618-907). Provided to China Daily