Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. TUI short for: Text User Interface or Textual User Interface (and sometimes Terminal User Interface), is a retronym that was coined sometime after the invention of graphical user interfaces, to distinguish them from text-based user interfaces. TUIs are different from command-line interfaces in that, like GUIs, they use the entire screen area and do not necessarily provide line-by-line output. However, TUIs only use text and symbols available on a typical text terminal, while GUIs typically use high-resolution graphics modes.