Local television stations (__not__ networks - although there are a small number, limited by law, of network owned-and-operated local stations - usually the biggest markets), which may or may not be affiliated with a network (CBS, NBC, Fox, ABC), broadcast the signals.<p>If a local station is affiliated with a network, they&#x27;ve agreed to broadcast the network&#x27;s prime-time feed (7pm - ~midnight) including the national ads that the network has sold to large brands.<p>The local tv stations get (not very many) ad spots to insert in between national ads.  The local tv station does not generally get any revenue from the national ads (the big ads for big brands - Coke, Apple, Nike) and only receive revenue from local ads (Stu&#x27;s burger shack down on main street).<p>There are also open slots where the national network does not have shows scheduled and local stations can broadcast locally produced shows, News, and, sadly, tons of infomercials.  This is the non-prime-time - daytime, weekends and late night.<p>If the show being broadcast is locally produced, there are generally more open ad slots for local ads.  It is possible that the local station also gets a cut of national advertising during that show.<p>The local TV station has purchased the exclusive right to use the frequency&#x2F;channel (in a particular &quot;market&quot;) from the Federal Government, but has to provide, as part of the agreement, a number of things, &quot;to promote the public welfare&quot; - such as educational programming, community service programming, and a few other things.