According to eMarketer.com, in 2012, mobile advertising was up 220% in the US. This figure includes both display advertising and PPC search advertising.
Display ads are brand-building ads, with text, logo and graphics, aimed more at getting your company’s name out there than actual conversions. PPC (Pay Per Click) ads, on the other hand, are those all-text “Sponsored Links” that appear at the top of search engine results pages. The most popular PPC service is Google AdWords.