The
twisted nematic effect (
TN-effect) was a main technology breakthrough that made
LCDs practical. Unlike earlier 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. In the meantime, many applications of LCDs are using alternatives to the TN-effect such as
in-plane switching (IPS) or vertical alignment (VA).