The Lantern Festival or the Spring Lantern Festival is a Chinese festival celebrated on the fifteenth day of the first month in the lunisolar Chinese calendar. It marks the final day of the traditional Chinese New Year celebrations, and falls on some day in February or March in the Gregorian calendar.

In the evening of 15th day of the first lunar month, on the night of the full moon, families gather for dinner and go out and see fireworks and light lanterns. Lanterns are put up for decoration, let loose to fly, and floated in rivers.

Source: https://en.wikipedia.org/wiki/Lantern_Festival, http://www.chinahighlights.com/travelguide/festivals/new-year-facts.htm