Is "Search" Advertising?

When I think of advertising on the web, I think of three different flavors:Search: Listings on Google or some other search engine.Display: Banners or other types of static or moving ad units.Social media: Advertising disguised as something else (blog, website, online community, etc.)The most effective seems to be "search." It accounts for over 40% of all on-line ad dollars. From what I've been