Much of what we in the West consider to be yoga is really just asana practice. Asana is a great entryway into yoga for most people because it helps to align the physical body and calm and strengthen the nervous system body and mind for more subtle practices.
Asana, alone or with vinyasa can be deeply healing for the body. When alone, each asana constricts, twists, or opens different parts of the body, and calls for the practitioner to find a calm, even breath.
Asana practice creates harmony and flow within the body. Twisting and forward folding can be deeply healing for the internal organs. Backbending can be healing for the spine and can help to move the kundalini energy. Posture practice as a whole is deeply purifying for the body and is a beautiful method of the Swadhyaya, self-study.
In the Ashtanga yoga method, asana is combined with vinyasa. One vinyasa could be a full Suryanamaskar A or the combination of Chaturanga, Updog, Downdog. Vinyasa creates flow within the body after each posture, moving toxins and pushing fresh blood into the recently opened areas.