Ask any digital marketer or marketing agency bod which discipline is first on the budget sheet, they're bound to answer 'search'. It stands to reason - although companies spend time, effort and money trying to tightly define their target audiences and deliver relevant messages at relevant times, a search audience is self-selecting.
Your ad is only served to those interested in your product or service as identified by the search phrase they enter into Google or Bing. By definition you've served the ad to the right audience at the right time.
