What are the Custom Variables?
Custom Variables let you squeeze out more from your Piwik PRO Analytics deployment, and it delivers advanced, customized reports to add depth to your stats. You can create a custom name-value pair assigned to any visitor or event. The only limit is your imagination! Here is an article, where you can find information on how to add custom variables.
For additional information about variables and different use cases, please check out our blog. Also, you can find the use cases right here.