(But not actually everything you need to know, because many others on the internet have talked about mewing EXTENSIVELY. I hope to flesh this page out with more resources eventually, but for now, this very basic primer was last updated 4/8/2019.
What is mewing?
“Mewing” is a term coined by followers of Mike Mew (and his father, John Mew) to describe all of the actions/exercises involved in developing and maintaining proper tongue (and to a lesser extent, lip/cheek/jaw) posture. In addition to keeping the tongue in its rightful place on the roof of the mouth, this also includes things like proper chewing/swallowing technique and various tongue exercises.
(That’s the broader definition. Alternately, “mewing” can sometimes simply refer to maintaining proper tongue posture on the roof of the mouth.)
Mewing has started to pick up steam as an underground/fringe movement, and is notably popular among incel communities. (If you aren’t familiar with the term “incel,” I’ll let urban dictionary educate you.)