Desktop ad impressions are where someone types in a search query like "Flat screen TV" and your website pops up in a minimized screen. The advertising is search generated just like pay per click but unlike pay per click the traffic only costs .12Cents per visitor as opposed to $2.50 per visitor with pay per click. Obvisously Desktop Ad Impressions are the cheaper alternative to pay per click but also present more advantages like lowering your cost per sale, eliminating click fraud, and being the only website that appears in search results. The disadvantages are that there are minimum buy in's for most companies starting at $1200 to $10,000. You get alot more traffic at not even a fraction of the cost for traditional pay per click advertising.