Bhakti yoga, also called Bhakti marga (literally the path of Bhakti), is a spiritual path or spiritual practice within Hinduism focused on loving devotion towards any personal deity. It is one of the three classical paths in Hinduism which lead to Moksha, the other paths being Jnana yoga and Karma yoga.
The tradition has ancient roots. Bhakti is mentioned in the Shvetashvatara Upanishad where it simply means participation, devotion and love for any endeavor. Bhakti yoga as one of three spiritual paths for salvation is discussed in depth by the Bhagavad Gita.
The personal god varies with the devotee. It may include a god or goddess such as Ganesha, Krishna, Radha, Rama, Sita, Vishnu, Shiva, Shakti, Lakshmi, Saraswati, Parvati, Durga, and Surya among others.
The Bhakti marga involving these deities grew with the Bhakti Movement, starting about the mid-1st millennium CE, from Tamil Nadu in South India. The movement was led by the Saiva Nayanars and the Vaisnava Alvars. Their ideas and practices inspired bhakti poetry and devotion throughout India over the 12th-18th century CE.Bhakti marga is a part of the religious practice in Vaishnavism, Shaivism, and Shaktism.
Devotion may also be impersonal as discussed in the book Narada’s Way of Divine Love written by Swami Prabhavananda.