Yoga, word used and abused in the West, is derived from the Sanskrit root yuj, which indicates terms such as union, bond, subjugate. For this yoga is "what binds the individual to the universal, the atman to the brahman, but it also what subdues the senses to allow this union.
Yoga is not only, as is believed in the West, a physical practice that includes a series of asanas (postures) for the well-being of the body. Yoga is one of the six orthodox darshana, philosophies or points of view of the Hinduism.
This doctrine is divided into eight disciplines, it speaks of the 'Eightfold Path', one of which is the one of the asanas or positions.
Understood in the sense of "practice" there are many types of yoga.
Another key word of Hinduism is diksha (or deeksha), which indicates the initiation, the moment when the boy of the three upper castes is introduced to the teachings of the guru (see etymology) or the ceremony of initiation into a particular Hindu discipline, with particular reference to Tantrism.
The deeksha is to be celebrated by a guru who whisper in the ear of the disciple the mantra (see etymology) that the young bring with him self and will repeat throughout his life. Without having received initiation, you can not even listen to certain teachings of the guru.
The etymology of diksha is not unique. Some people derives from the Sanskrit root da which means to give and from the root kshi which means to destroy. In this sense, the term diksha refers to the destruction of life and the gift of another one, a kind of rebirth that is confirmed by the fact that members of the three upper castes are called after initiation dvija ie, twice-born.
Other etymology of the word diksha derive from the root diks which means to consecrate or to dedicate.