keywords from being eligible for ad targeting as part of a policy to prevent companies from attempting to capitalize on the pandemic. Cost Every time a user conducts a search on Google, Google Ads runs an auction in real time to determine which search ads are displayed on the search results page as well as the ad's position. The cost of a Google Ads campaign therefore depends on a variety of factors, including the maximum amount an advertiser is willing to pay-per-click the keywords being bid on, and the quality score of the ad (based on its relevance and click frequency and ad extensions). Although an advanced bidding strategy can be used to automatically reach a predefined cost-per-acquisition (CPA), this should not be confused with a fixed CPA pricing model. Conversion tracking In addition to tracking clicks, Google Ads provides advertisers an ability to track and report other conversions that happen after the click such as purchases, sign ups or calls. Conversion tracking is implemented by sending an identifier to the advertiser's website as a URL parameter, which is then used by advertiser to send conversions to Google Ads, allowing Google Ads to trace conversion back to the original click for reporting. Google also allows advertisers to install a pixel on their website that sends conversions to the Adwords account. This allows advertisers to target their ads to drive conversions more effectively. For most traffic, Google sends a unique identifier for each click (in a gclid parameter), allowing to determine source of conversion precisely. To comply with tracking restrictions on Apple devices, anonymized identifiers that aren't associated with specific person are used (called wbraid and gbraid). Google Ads provides ability to report many of such anonymous conversions by using "modeled conversions" that combine additional customer details to deduce, which user to attribute the conversion to. Google Ads introduced enhanced conversions to make conversion measurement more accurate. Lawsuits Google Ads have been the subject of lawsuits relating to trademark law (Google, Inc. v. Am. Blind & Wallpaper Factory and Rescuecom Corp. v. Google Inc.), fraud (Goddard v. Google, Inc.), and click fraud. Overture Services, Inc. sued Google for patent infringement in April 2002 in relation to the AdWords service. The suit was settled in 2004 after Yahoo! acquired Overture; Google agreed to issue 2.7 million shares of common stock to Yahoo! in exchange for a perpetual license under the patent. In