CBS
From The Big Bang Theory Wiki
CBS is an American television network, part of the "big three" networks (the others being NBC & ABC). CBS is colloquially referred to as "The Eye" because of its logo, which features an eye.
CBS is currently the most popular American network, coming top the of the Nielsen ratings for a number of years with hits like 'Two and a Half Men' & 'CSI'. CBS did suffer a rout in the mid-90s though, with it perceived to be an old-fashioned network.
CBS is currently run by Les Moonves, and has been from 1998. CBS is owned by the CBS Corporation, the new name of what was previously Viacom. Viacom is now a separate company which focuses solely on movie production & distribution along with satellite & cable channels.