Definition:
Defining the term "Yoga" is difficult as different cultures and different religions have different senses for Yoga.

Following are some definitions:

According to Hinduism:
The term refers to a set of ancient spiritual practices origination in India that gives a concept of asceticism and mediation that develop spirituality. That is, asceticism refers to abstaining from mundane things and practices, such as eating food, attending ceremonies etc. Asceticism restricts its followers not to take part in world and mundane routine.

Outside India, the term refers to postures or asana. In Sanskrit, asana refers to seats, it is not imply the physical seat but it implies the seat of spirituality. If someone practices, yoga, it will sit on spiritual seat.

In this modern era, yoga is a set of exercise that relax your muscles both externally and internally (mentally and physically), gives you extra strength and mental piece.

In this website, you will learn all about Yoga, how to perform it and what you need to practice Yoga. As it is a set of exercise, you need its special dress, special tools and instructions to perform Yoga.

Conclusion:
Yoga is a set of exercise that gives you muscular relaxation and mental piece. In order to perform Yoga, you need its special dresses and tools with proper instructions.