Overview
Rath Yatra (literally "Chariot Festival" or "Car Festival") refers to any public procession in a chariot. Such processions are held annually during festivals in India, Bangladesh, Nepal, and Sri Lanka. The term most popularly denotes the annual Ratha Yatra of Puri in the state of Odisha, which involves a procession of the deities Jagannath (an avatar of Vishnu), his brother Balabhadra, his sister Subhadra, and the Sudarshana Chakra (his weapon), placed on a wooden, deula-shaped chariot known as a ratha.
Historically, Ratha Yatra processions have been common in Vishnu-related traditions of Hinduism, such as those dedicated to Jagannath, Rama, and Krishna, particularly in Puri. They are also observed in Shiva-related traditions, in honour of saints and goddesses in Nepal, in connection with Tirthankaras in Jainism, and among tribal folk religions in the eastern states of India. Notable Ratha Yatras in the region include the Ratha Yatra of Puri, the Dhamrai Ratha Yatra in Bangladesh, and the Ratha Yatra of Mahesh.
Hindu communities outside the Indian subcontinent, including those in Singapore, also celebrate Ratha Yatras, including processions associated with Jagannath, Krishna, Shiva, and Mariamman. According to scholar Knut Jacobsen, while the Ratha Yatra has religious origins and meaning, the events also carry significant community heritage, social sharing, and cultural importance for organisers and participants.
The Jagannath Ratha Yatra of Puri has had a notable cultural impact beyond India. Western impressions of the procession as a display of unstoppable force are the origin of the English word "juggernaut".
References
Adapted from the English Wikipedia article on Ratha Yatra.