Actually I’m sure it is a Cafe Society question. Launching a new TV show is directly related to the content and viewership of existing TV shows. Existing shows are discussed and analyzed frequently and in minute detail in Cafe Society.
To answer your question:
Normally, the only people allowed to pitch TV shows to networks and films studios are experienced TV writers - people who’ve been working on the writing staffs of existing TV shows for several years.
The exceptions are screenwriters and directors of hit feature films, star actors from both TV and film, as well as writers who’ve had huge success in some other pop culture area. Anthony Zuiker -CSI- was a feature film screenwriter w/ no TV experience. Aaron Sorkin was a feature film writer and playwright with no TV experience. Stephen King, novelist, obviously, Aaron McGruder (Boondocks comic strip), Dave Barry (widely syndicated columnist and best selling author).
Generally speaking, nobody buys a TV show idea. The networks, film studios, and production companies buy pilot scripts. A pilot script is the script for the first episode of the show. The pilot script both introduces the world of the show, and all the elements that make a typical episode of the show.
Every year, thousands of experienced TV writers go into the various offices to pitch their ideas. (google “pilot season)”
Out of those thousands, a few hundred are assigned and paid to write pilot scripts. Out of those scripts, less than a hundred get made into actual first show episodes. Out of that number, less than thirty new shows actually show up on the new fall schedule, and most of those won’t last a year.
If you’re really sure you’ve got a brilliant idea, you can shoot the pilot yourself. Write the script, cast the actors, find the sets, put up all the cash, organize the whole venture just as you would with a low budget indy film. That’s how It’s Always Sunny in Philadelphia got started. Not impossible, but not very likely.
This is a rough overview. There are details and variations if you need more info.