What are Dimensions?
Unlike quantitative metrics, dimensions are descriptive attributes of your data. They are typically text-based and provide additional information about your metrics.
Let's take a closer look at those 111,444 sessions from earlier.
You can see that 105,513 of those sessions came from Google, with smaller amounts coming from "(direct)" (i.e. people who came directly to your site, such as by phone number in korea entering your URL into their browsers) and Bing.
Data displayed for session sources "google", "direct" and "bing"
The source of those sessions is called the Session Source dimension, and you can see how it provides new insights into our metric.
This is one dimension of traffic source, but you'll find there are many more.
Note
Traffic source dimensions can be session or user-defined. If you're interested, you can read more about user-defined dimensions in this Google support article , but in this article we'll focus on the most common session-defined dimensions.
Ways to classify traffic sources in Google Analytics
Google Analytics classifies traffic in different ways to provide multiple layers of analysis. These different classifications are dimensions of the traffic source.
There are five dimensions of traffic source that you need to know.