What a Custom Variable is: In Google Analytics terms, a custom variable is a tag that you can insert in your tracking code in order to define additional segments to apply to your visitors (other than the ones GA already provides).
What a Custom Variable is not: a push-button solution– it involves a little finesse, and some coding in order to get everything set up right!
Why we care about Custom Variables: A custom variable can help you to track information at several different levels. You can track activities that your visitors perform on a page-level, or even categorize your visitors across multiple sessions. It’s powerful stuff, and once you know what you want to track, chances are there’s a way to set up a custom variable to track it!
This post is part of an ongoing Clickipedia series, defining all the terms you need to know for conversion rate optimization. Keep checking back each week to learn more, and don’t forget to check out the whole series.