“While the built-in dimensions are great, there are many dimensions that would be incredibly useful that are not tracked by analytics.js. Luckily, Google Analytics has a feature called custom dimensions, so you can implement and track whatever dimensions you want.”— Philip Walton, philipwalton.com
“Instead of implementing outbound link tracking ourselves, we used the autotrack plugin to do this for us. Autotrack comes with a set of plugins for tracking common user interactions. Theres a bunch of things it can help with, but the main one we wanted was the outboundLinkTracker plugin.”— Chris Coyier, css-tricks.com
“The easiest way to send custom dimension data with your hits is to set their values on the tracker object. Since all hits sent from a tracker include all the key/value data it's currently storing, setting custom dimensions on the tracker will ensure those values get sent with all future hits.”— Chris Coyier, css-tricks.com