Traditional acupuncture theories are based around the concept of Qi, which is essential for life, also described as life force, energy, vitality depending on the context. In TCM, Qi travels around the body via meridians or channels. These channels correlate to different organs, systems and aspects of a human being, so a practitioner may ask about your life and health from different perspectives and the focus is on the whole individual rather than a particular sign or symptom in isolation. In practice this means when treating headache, for example, an acupuncturist may wish to understand whether there are any problems with the digestion. If there are problems, this will change the diagnosis and result in the selection of different acupuncture points.