The twisted nematic effect (TN-effect) was a major technological breakthrough that made the manufacture of large, thin liquid crystal displays practical and cost competitive. Unlike earlier flat-panel displays, TN-cells did not require a current to flow for operation and used low operating voltages suitable for use with batteries. The introduction of TN-effect displays led to their rapid expansion in the display field, quickly pushing out other common technologies like monolithic LEDs and CRTs for most electronics. By the 1990s, TN-effect LCDs were largely universal in portable electronics, although since then, many applications of LCDs adopted alternatives to the TN-effect such as in-plane switching (IPS) or vertical alignment (VA).
Many monochrome alphanumerical displays without picture information still use TN LCDs.
TN displays benefit from fast response times and less smearing than other LC display technology, but suffer from poor color reproduction and limited viewing angles, especially in the vertical direction. Colors will shift, potentially to the point of completely inverting, when viewed at an angle that is not perpendicular to the display. Viewing the display from above whitens colors, and viewing the display from below dims colors.