The discrepancy among the searches you propose your ad to turn for and the actually searches that trigger your ad is as the AdWords system uses various match types for key phrases. There are four main match types: broad, broad match modifier, phrase, and exact. The alternative match types allow you the small enterprise advertiser to compare for a broader or narrower range of tangible search queries that users type in. Broad is as it sounds probably the most broad in terms of what searches trigger your ad, and it is ALWAYS set by default in Google AdWords. This means that it is at Google’s discretion to come to a decision that a user’s search is “close enough” for your key phrase.
Since Google gets paid on every click, they have a broad view of what’s close enough. For instance, let’s say you are in the correct industry for a right away sale, like a winter apparel store that sells winter hats among other items. If you are only delivery to use AdWords you might send all the users on your usual homepage. If you purchase the key phrase winter hats and the user is shipped to the homepage, which is crowded with all of your items, the user has to look find the specific sales page for winter hats. This means the user had to spend extra mental energy to look more through your web page and click again.
The majority of users won’t expend this mental energy– they leave your page without making a purchase.