Fun fact: a lot of the content you see on big sites are advertorials, this means some company writes a fluff piece about how their lastest product can solve all your problems, and then pays the site to publish it. In print, you even have the option to have the ad use the same layout, fonts, colors etc. as the real content.

This means a portion of a site is not filled by content that had to be bought, but actually brings them money.