Hatha Yoga is a kind of yoga that is practiced in India.
Yoga is a religious practice based on a sequence of physical
postures called asanas.
It is commonly thought that practicing this yoga provides a
variety of physical advantages, including enhanced physiological flexibility
and the potential to treat chronic diseases.
These asanas, however, are just one aspect of an eight-step
regimen that also includes breathing exercises and meditation, according to
Patanjali's Yoga Sutras, the oldest systematic study of yoga.
Hatha yoga's goal is to strengthen and condition the body so
that the practitioner can sit comfortably in meditation.
Although Hatha yoga focuses on the body, it also implies a
spiritual and religious background that is frequently omitted or overlooked in
modern times, causing some Hindus to dismiss it as just a practice for
improving sexual control.
The Nathpanthi ascetics interpret hatha yoga as relating to
processes in the subtle body, giving it a more esoteric connotation.
The subtle body is an alternative physiological system that
is said to exist on a distinct level of existence than the physical body, yet
has certain similarities to it.
The aspirant aims to combine kundalini with the Shiva
principle at the crown of the head; through this union, the physical body will
become immortal.
It is visualized as a set of six psychic centers (chakras)
running roughly along the course of the spine; above and below these centers
are found the two divine principles, Shiva (awareness) and Shakti (power), the
latter as the latent spiritual energy known as kundalini.
The phoneme ha, according to the Nathpanthis, relates to the
sun, which is a sign for Shakti, and the phoneme tha, which is a symbol for
Shiva.
Hatha yoga is said to be the union of the sun and moon, or the presence of these two power centers in the subtle body.
You may also want to read more about Hinduism here.
Be sure to check out my writings on religion here.