A custom variable is defined by a name — for example, “User status” — and a value – for example, “LoggedIn” or “Anonymous”. You can track up to 5 custom variables per visit and/or up to 5 custom variables per page view.
Some common use cases for custom variables are:
Custom variable names and values are limited to 200 characters in length. We recommend that you store values that are as small as possible to ensure that the Piwik Tracking request URL doesn’t go over the URL limit for the web server or browser.
You can access the custom variable reports in the visitors menu. Piwik reports all the standard metrics: unique visitors, visits, pages, time on site, bounce rate, conversion rate, revenue, etc. These reports are for each custom variable name, and also for each custom variable value. For custom variables of scope “page”, Piwik will report the following metrics: unique visitors, visits, pages.
In the example below, we created a custom variable name = ‘Demo language’, with the value being the language the visitor is using on demo.piwik.org
Custom variables which have a scope “page” will appear in the tooltip when you hover on the Page URL or Page Title in the Visitor Log.
Custom Variables are useful to track detailed metadata about the Pages, events or visitors. Here are some more information about the data limits in use: