Mewing is a type of oral posture training (strengthen your jaw line) made to improve the jawline and the look of your face. It was named after John and Mike Mew, British orthodontists who made the technique as a part of a practice they call "orthotropics". Mewing is done by placing your tongue at the roof of the mouth (which is called the palate) and putting a bit of pressure there. Also, you should swallow the fluids in your mouth while mewing. This is done with the goal of changing the structure of the jaw. However, no credible scientific research has ever proven how well orthotropics work. Since 2019, mewing has had a lot of media coverage due to it becoming viral on social media, especially with what is known as looksmaxxing. Looksmaxxing is when someone tries to improve how they look. This is usually done by improving their habits. While the technique has been known to have some positive effects, many orthodontists say that mewing does not have enough evidence as a good alternative treatment to orthognathic surgery. Mike Mew has been kicked out from the British Orthodontic Society, and is currently facing a legal hearing for allegedly harming child patients who he treated.

Mewing has been used as an internet meme. On social media platforms such as TikTok, people will point to their jaw to show that they are mewing in their videos.[source?] In reference of how Donald Trump in a 2023 mug shot looked, journalist Bindu Bansinath wrote "perhaps he's mewing for better definition."