A guru ( , , ) is a person who is regarded as having great knowledge, wisdom and authority in a certain area, and who uses these abilities to guide others. It also means "teacher" or "guide" in the religious sense, and is commonly used in Sikhism, Buddhism and Hinduism as well as in some new religious movements.

In the eastern traditions, mothers are held to be the primordial guru of each human being, and human gestation is considered a highly relevant phase of spiritual learning and adept potential. Thus, the mothers of any saints, mahatmas, or yogins are revered and even meditated upon. The guru is seen as a conduit for sacred wisdom and guidance, and finding a true guru is often held to be a prerequisite for attaining self-realization. The gurudev is the concept of one's highest consciousness as an inner teacher or intuition within the student.

The dialogue between guru and student is a fundamental component of Hinduism, established in the oral traditions of the Upanishads (c. 2000 BC). In the Upanishads, the guru-disciple relationship appears in many settings. Sometimes the sages are female, and sometimes the instruction is sought by kings. Examples include the relationship between Krishna and Arjuna in the Mahabharata (Bhagavad Gita), and between Rama and Hanuman in the Ramayana.

In contemporary India, Malaysia, Brunei and Indonesia, the word "guru" is widely used with the general meaning of "teacher", including by schoolchildren. In Western usage, the meaning of guru has been extended to cover anyone who acquires followers, though not necessarily in an established school of philosophy or religion. Forsthoefel, T. and C. Humes. Gurus in America (2005) p.3. SUNY Publishers ISBN 0-7914-6574-8 In a further Western metaphorical extension, guru is used to refer to a person who has authority because of his or her perceived secular knowledge or skills.

The guru-shishya tradition

main: Guru-shishya tradition

The guru-shishya tradition is the transmission of teachings from a guru (teacher, ) to a 'IAST: śiṣya' (student, ). In this relationship, subtle and advanced knowledge is conveyed and received through the student's respect, commitment, devotion and obedience. The student eventually masters the knowledge that the guru embodies, creating an exponential increase of wisdom on the earthly plane. In the Vedas, the brahmavidya or knowledge of Brahman is communicated from guru to shishya through the spoken word.

Classification of gurus

According to the Deval Smriti there can be eleven kinds of gurus and according to Nama Chintamani there are ten types.