One of the hottest markets driving physics research is the demand for a perfect visual display. People want, for example, large, thin, lightweight screens for high-definition TV and outside displays, very high-resolution flat computer monitors that are robust and use little power, and mobile phones with colourful micro-displays that are 'bistable' - which means they remain visible when switched off. Several types of flat display are competing for these applications - a market currently worth about $20 billion a year but expected to double in the next five years. Not surprisingly, the research departments of universities and the big electronics companies around the world are bustling with exciting ideas and developments, of which just a few are mentioned here. Many new devices are being developed by new university spin-out companies.