Meditation has been defined as self regulation of attention, in the service of self-inquiry, in the here and now. The various techniques of meditation can be classified according to their focus. Some focus on the field or background perception and experience, often referred to as mindfulness. Others focus on a preselected specific object, and are called concentrative meditation. There are also techniques that shift between the field and the object.
In mindfulness meditation, the meditator sits comfortably and silently, centering attention by focusing awareness on an object or process such as the breath, a sound such as a mantra, or a koan or riddle-like question. The meditator is usually encouraged to maintain an open focus.
Concentration meditation is used in many religions and spiritual practices. Whereas in mindfulness meditation there is an open focus, in concentration meditation the meditator holds attention on a particular object such as a repetitive prayer, while minimizing distractions and bringing the mind back to concentrate on the chosen object.
Meditation can be practiced while walking or doing simple repetitive tasks. Walking meditation helps break down habitual automatic mental categories, thus regaining the primary nature of perceptions and events, focusing attention on the process while disregarding its purpose or final outcome. In a form of meditation using visualization, such as Chinese Qi Gong, the practitioner concentrates on flows of energy in the body, starting in the abdomen and then circulating through the body, until dispersed. Some meditative traditions, such as yoga or tantra, are common to several religions.