Kathina is a word from the Pali language referring to the wooden embroidery frame used in India to make Monks' robes that came to be known as Kathina Robes. It is observed in countries of Theravada tradition such as Thailand, Burma and Sri Lanka. It is a ceremony where lay people present robes to the Sangha after their period of observance of three months retreat in the temple during the rainy season and it originated during Buddha's time.
It was stated that the robes of a group of monks were ruined in the heavy rain while on their way to see the Buddha at the Jetavana monastery. It was the rainy season then and seeing their plight, the Buddha decided to allow his disciples to accept a robe or piece of cloth for making robes at the end of the rainy season (vassa).
This tradition has continued to this day by temples who are of the Theravada tradition. In addition to robes, devotees also present basic requisites eg toothpaste, toothbrush, medicine to the Sangha. The benefit of the Kathina ceremony is one of mutual support between the Sangha and lay persons. For the lay persons, it is a special opportunity to make merits.