How can service to others make you great?

How can advertising be applied to a service to make that service free for others?

• "Google and Facebook are the obvious examples using the current business model, whereby their products are provided for free to users while revenue is derived from 3rd-party advertisers." I know it's easier said than done. But I once heard of a taxi service being offered free in certain places, and the way the company made money was to place ads on tablets or in the cab for riders to view. Can this concept be applied to other things successfully. If so how?

• Answer:

  Just a in any kind of media, adds pay for he cost of publishing. Adds on newspapers, regular non-cable tv and websites make content free-of-cost for final users. The more adds, the more "sponsored" the media is, thus the less it will try to get funded by subscribers.