It's a bit more than just advertising, though. Facebook and Google both run ad networks. Both publishers [other websites] and advertisers can turn to either [or

It's a bit more than just advertising, though. Facebook and Google both run ad networks. Both publishers [other websites] and advertisers can turn to either [or both] for their advertising needs. This is also why Snapchat has a billion dollar valuation [see how many views they send Buzzfeed http://www.businessinsider.com/buzzfeed-gets-21-of-its-traffic-from-snapchat-2015-9 http://www.businessinsider.com/buzzfeed-gets-21-of-its-traff...]