Tomb sweeping day (清明)

Qingming Festival of 2015 falls on April 5. 
Cleaning the tomb and paying respect to the dead person with offerings are the two important parts of remembering the past relatives. Weeds around the tomb are cleared away and fresh soil is added to show care of the dead. The dead person's favourite food and wine are taken to sacrifice to them, along with paper resembling money. This is all burned in the hope that the deceased are not lacking food and money. Kowtow before the tablets set up for the dead are made. (read more about kowtow at http://en.wikipedia.org/wiki/Kowtow)
Today, with cremation taking over from burying, the custom has been extremely simplified in cities. Only flowers are presented to the dead relatives and revolutionary martyrs. No matter how respect is shown, good prayers for the deceased are expressed.

Origin
It is said that the Qingming Festival was originally held to commemorate a loyal man living in the Spring and Autumn Period (770 - 476 BC), named Jie Zitui. Jie cut a piece of meat from his own leg in order to save his hungry lord who was forced to go into exile when the crown was in jeopardy. The lord came back to his position nineteen years later, and forgot Jie Zitui but later felt ashamed and decided to reward him. However, Jie had blocked himself up in a mountain with his mother. In order to find Jie, the lord ordered that the mountain should be set on fire. Later Jie was found dead with his mother. In order to commemorate Jie, the lord ordered that the day Jie died was Hanshi (Cold Food) Festival - the day that only cold food could be eaten.
The second year, when the lord went to the mountain to sacrifice to Jie, he found willows revived, so he gave instructions that the day after Hanshi Festival was to be Qingming Festival. Later, the two festivals were combined as one.
read more at wiki.