LCD TV ...
LCD technology is based on manipulation of polarized light. Two thin polarizing sheets are laminated to two glass substrates containing a thin layer of liquid-crystal. A regular 2-dimensional grid of electrodes allows each pixel in the array to be selected and activated individually. Several LCD technologies are used for the realization of large format television screens (e.g. TN, IPS, PVA, FFS), all in combination with active-matrix addressing.
It had been widely believed that LCD technology was suited only to smaller sized flat-panel televisions at sizes of 40" or smaller. Early LCDs could not compete with plasma technology for screens larger than this because plasma held the edge in cost and performance. However, LCD TVs can now offer acceptable performance in larger sizes...
HDTV ...
High-definition television is a digital television broadcasting system with higher resolution than traditional television systems(standard-definition TV or SDTV).
HDTV is digitally broadcast; the earliest implementations used analog broadcasting, but today digital television (DTV) signals are used, requiring less bandwidth due to digital video compression.
