Google Analytics provides source and medium information for all sessions and transactions. Source is the origin of your traffic, such as a search engine (for example, google) or a domain (example.com). Medium is the general category of the source, for example, organic search (organic), cost-per-click paid search (cpc), web referral (referral). This insight breaks down the revenue by the source and lists the different sources highest to lowest based on the amount of revenue they generated. Knowing which sources leads to maximum revenue and higher conversion rate helps you focus on that and make it more effective. In cases where a source does not contribute to any revenue, it will be ordered by the number of sessions the source contributed to.