Somatics is the study of the self from the perspective of one’s lived experience, encompassing the dimensions of body, psyche, and spirit.
—Thomas Hanna

For the first time, he made a distinction between the body and the soma.
He defines them as two distinct viewpoints for observing a human, the body as a phenomenon perceived from the outside, so from a third-person perspective.
And the soma instead is the body internally perceived, so from a first-person perspective.

As humans, we are equally capable of being internally self-aware as well as externally aware, for instance, the body is what we see when we look ourselves in the mirror, the soma instead is the pool of sensations we feel in any moment.

Somatic approaches are used in several fields including psychology, movement, dance, and bodywork:

Somatic psychology, also called body psychotherapy, moves beyond talk therapy to include the felt experience of a person in their body as a primary means of understanding what’s going on in the mind.
In this group, we can find Somatic Experiencing, Integral Somatic Psychology, Bodynamic, and many others.

Somatic bodyworks use touch to help a person develop their internal awareness and address physical or emotional pain.
In this group, we can find the Feldenkrais Method, Alexander Technique, Ilan Lev Method, Body-Mind Centering, Rolfing Structural Integration, Trager Approach, and many others. Most of these approaches also provide group movement classes.

Somatic dance and movement practices emphasize the internal experience of the dancer as opposed to dancing for how it looks to those who are watching. 

In this group, we can find Contact Improvisation, Authentic Movement, Skinner Releasing Technique, Ideokinesis, and many others.

Developing the ability to observe our body from an internal perspective can allow sensing the level of muscle tension in the body, in this way we can have a starting point to work to release them.

And through the experience, exploration, and investigation of the sensations in the body, we can develop a better sense of self-care.

By releasing held tensions, paying attention to the present moment, and regulating the nervous system, a somatic approach helps ease the feelings of arousal and disconnection that can arise during the high-stress periods of our life.