This emoji depicts a yellow face with a frowning mouth, scrunched eyebrows, and angry-looking eyes, which is typically used to convey feelings of anger, frustration, or annoyance. The stern expression, furrowed brow, and clenched jaw or gritted teeth are all intended to convey the person's anger or frustration.
Samsung's earlier design of this emoji featured a reddish face with clenched teeth and a wrinkled chin, while Google's previous design also featured a reddish face. Facebook's and Microsoft's earlier designs had clenched teeth as well.
The Angry Face emoji was approved as part of Unicode 6.0 in 2010 and added to Emoji 1.0 in 2015.
U+1F620