Ghostery looks for third-party page elements (or trackers) on the web pages you visit. These can be social network widgets, advertisements, invisible pixels used for tracking and analytics, and so on. Ghostery Inc. sells the tracking data that users (who volunteer for this) gather from sites they visit to make their sites more secure and load faster. The option to share your data is called GhostRank and can be disabled/enabled during install or at a later moment under General Options”]
Source: https://blog.malwarebytes.com/cybercrime/2015/09/ghostery-a-tool-that-stop-trackers/