Overview
The Gāyatrī Mantra, also known as the Sāvitrī Mantra, is a sacred mantra from the Ṛig Veda (Mandala 3.62.10), dedicated to the Vedic deity Savitr. It is traditionally attributed to the brahmarshi Vishvamitra. Within Hindu tradition, Gāyatrī is also the name of the goddess associated with the mantra, as well as the name of its Vedic metre.
The term Gāyatrī may further refer to a class of mantras that follow the same Vedic metre as the original Gāyatrī Mantra (without the first line). Many such Gāyatrīs exist for various gods and goddesses, forming a wider devotional repertoire across Hindu traditions.
The mantra is cited widely in Hindu textual sources, including the mantra listings of the Śrauta liturgy and classical works such as the Bhagavad Gita, the Harivamsa, and the Manusmṛti. It is also recorded that the mantra and its associated metric form were known to the Buddha, indicating its currency in the broader religious milieu of ancient India.
Traditionally, the Gāyatrī Mantra forms an important part of the initiation (upanayana) ceremony, during which it is imparted to the initiate. Modern Hindu reform movements played a significant role in extending the practice of the mantra to a wider section of society, and its recitation is now very widespread among Hindus.
References
Adapted from the English Wikipedia article on the Gayatri Mantra.