LCoS is short for Liquid Crystal on Silicon.
It’s quite similar to DLP in a number of ways, but instead of tiny mirrors embedded on a semiconductor, it actually uses liquid crystals. LCoS is also similar in this way to standard LCD technology with the exception of being able to produce much higher resolution and higher contrast images.
LCoS is the most mature of these projection technologies, stemming from a project by General Electric in the late 1970s.
It is also the responsible technology for the large scale production of the large and inexpensive flat panel displays that we enjoy in our homes.