I love doing yoga, it is so relaxing and calming!  I especially like Hatha yoga and Rāja yoga
That's great! What exact are Hatha and Raja yoga? What are the differences?
Rāja yoga is sometimes called "royal yoga" or "classical yoga" while Hatha yoga is mainly supplementary physical techniques within the broader concept of Yoga.
I'm not very familiar with yoga. What is the basic concept or classical approach?
Yoga
Yoga (; ; ) is a group of physical, mental, and spiritual practices or disciplines which originated in ancient India. Yoga is one of the six orthodox schools of Hindu philosophical traditions. There is a broad variety of yoga schools, practices, and goals in Hinduism, Buddhism, and Jainism. The term "yoga" in the Western world often denotes a modern form of Hatha yoga, yoga as exercise, consisting largely of the postures called asanas.
The origins of yoga have been speculated to date back
. In Hinduism, practices include Jnana Yoga, Bhakti Yoga, Karma Yoga, Laya Yoga and Hatha Yoga.
Traditions Classical yoga.
What is often referred to as Classical Yoga or Astanga Yoga (Yoga of eight limbs) is mainly the type of Yoga outlined in the highly influential "Yoga Sutras of Patanjali." The origins of the Classical Yoga tradition are unclear, though early discussions of the term appear in the Upanishads. The name "Rāja yoga" (yoga of kings) originally denoted the ultimate goal of yoga