Author Nick Black has written an extensive book on the creation of textual
user interfaces using the notcurses library; it’s available under the Apache
license [PDF]. “Many people asked how such a thing was
useful. My usual response was that numerous devices don’t present a bitmap
interface, that X11 GUIs run remotely over SSH are effectively unusable,
that plenty of machines don’t have a GUI environment installed, that there
are obvious applications for large outdoor displays, and that Sixel isn’t
well-supported across different terminal emulators. It seems impossible in
an age of gigatransistor graphics cards, but the text environment still
presents perceivably less latency than most GUI toolkits.“

Source: LWN.net – Hacking the planet with Notcurses