Sometimes the connection is via modem or terminal server, etc. Such terminals are not feasible to use with Linux. See section Block Mode . None of these are really graphics terminals. Vector graphic displays use smart electronics to draw lines and curves with an electron beam that can move in any direction.
Vector graphics draws high quality lines without zig-zags but is both rare and expensive.
Raster graphics is almost universally used today. Most of this document also applies to these. Most of these can also function as text terminals. None of these covered in this document. A terminal that deserves to be called smart is a graphics terminal which can rapidly display full-screen graphics just like a PC monitor.