The annual Qingming Festival (清明节) or Tomb Sweeping Day (掃墓節) occurs this year on April 4, 2024. 

Qingming Festival
Burning incense
Gathering of willow branches
Flying kits
Issued by China Post April 5, 2010

This traditional Chinese festival is celebrated in many countries, including China, Hong Kong, Macau, Taiwan, Malaysia, Singapore, Cambodia, Indonesia, Philippines, Thailand, and Vietnam. It dates back 2,500 years, Among the activities is a visit to ancestor’s tombs to pay their respects.

People commemorate and show respect to their ancestors by visiting their graves, and offering their spirits food, tea or wine, burning incense, burning or offering joss paper (representing money), etc. They sweep the tombs, remove weeds, and add fresh soil to the graves. They might plant willow branches, flowers, or plastic plants on the tombs. Qingming Festival 2024: What happens on Tomb Sweeping Day (chinahighlights.com)

A popular activity during such spring outings is kite flying. In ancient times, people used to tie pieces of paper with lists of their ailments and problems to a kite. They would then cut the string once the kite was high in the air and let it soar away, believing this to fend off misfortune and evil spirits. Ching Ming Festival, or tomb-sweeping day: what it signifies, how it is celebrated, and the awful deed behind its customs, according to legend | South China Morning Post (scmp.com)