The festival is celebrated in various countries such as Bangladesh (known as Kaṭhina Cībar Dān), Cambodia, Laos, Malaysia, Myanmar, Singapore, Sri Lanka, India, Thailand, and Vietnam. The season during which a monastery may hold Kathina is one month long, beginning after the full moon of the eleventh month in the Lunar calendar (usually October).
During this festival, the locals offer flowers and new robes for the monks as well as pray for good climate and happiness.
On the first festival day, before offering monks new robes, followers give offerings to Buddha while monks and nuns hold a national flag-hoisting ceremony and sing the national anthem in the Khmer language. After that, monks and nuns will pray for peace and good luck for locals.
On the second day, followers join a procession around the locality to prove their loyalty and later in the evening, they will be entertained with artistic programs in the pagoda.
According to Wikipedia, en.qdnd.vn