Google Analytics, which places a cookie on your device, to obtain metrics on how users engage with our websites. This helps us to improve site content. </li> <li>Optimizely and ShareProgress, which place a cookie on your device, to help us test variations of web content. This helps us offer better web experiences to users.</li> <li>DoubleClick and Flashtalking, each of which uses a clear GIF on our download Firefox page. This helps us measure the effectiveness of our advertising campaigns.</li> <li>Yahoo Dot Pixel, which uses JavaScript on our download Firefox page. This helps us measure the effectiveness of our advertising campaigns. </li> <li>HTTP Referral Data, which may be included with Firefox’s installer, to understand the website domain or advertising campaign that referred you to our download page. This information helps us understand the effectiveness of our advertising campaigns and improve them.</li> <li>Other metrics tools from time to time, on an experimental basis. For example, we may do this to help evaluate a new metrics tool, or test existing metrics collection.</li>