Terminal or Vi hangs after pressing ctrl + s

People who used to editors with shortcut CTRL + s to save files may have developed a habit to hit CTRL + s reflexively. 

I do the same. So, when I was using Vi, I may also accidentally pressed CTRL + s, which paused my terminal. Don't worry. Everything is fine. Simply press CTRL + q and the terminal will resume.

Picture: Pumpkins in Minnesota Arboretum. Oct. 2017