Well, to be decent, all body therapist have always been dealing with myo-fascial techniques.

Since 10 to 30 years, new attention has been given to that connective tissue and new perspectives on treatments & massage have arisen. 

To learn more about fascia : here is the word of Tom Myers (my reference). As  it is all over the web, it would be presomptuous to sum it up for you.

The technique is manual (massage) and is based on the theory that, through manipulation, one can reach deeper layers of soft tissue and impact them. It uses the patients actions and feedback to optimise its application (it is not a passive massage).

It is central in the Postural Transformation process as a guide (treatment strategy & evaluation) in combination with imports from my experience of postural yoga.
Myo means muscle & fascia is about all and any conective element between any subpart of your body : from muscle wrapers, tendons, ligaments but also deeper to muscle fibers to intercell matrix to etc.
Fascia, it has become one of the hottest words in the world of manual therapy,....

From Danny Adams, a Chiropractor at the Longlevens Chiropractic and Sports Injury Clinic in Gloucester

Read a here a one pager on "what myo fascia are"
​Myofascial Release is a safe and very effective hands-on technique that involves applying gentle sustained pressure into the Myofascial connective tissue restrictions to eliminate pain and restore motion.

​From https://www.myofascialrelease.com/about/definition.aspx