The most interesting places to use Custom Variables are in Segments or Calculations. These two areas help you capture data about users’ visits to pages containing the Custom Variable’s values and then display the information you capture in reports.
You must include Custom Variables in your Campaigns in order to capture data and report on it. Select them the same way you do any other Metric on the What to Measure tab.
Once you have created a Custom Variable, you can use it for: