Public broadcasting involves radio, television and other electronic media outlets whose primary mission is public service. In many countries of the world, funding comes from governments, especially via annual fees charged on receivers. Inform, educate and entertain.

what is the difference between private and public:

A public broadcaster is owned and supported by the general public. The TV license is paid by the general public, financing all of the general public broadcasters. A commercial broadcaster is privately owned and they finance themselves through advertisements.

channels:

The public service broadcasters are those providing Channel 3 services, Channel 4, Channel 5, S4C and the BBC. While all BBC public service television channels are PSB channels, only the main channels of each of the other public service broadcasters have this status.