A classification is a way of categorizing Analytics variable data, then displaying the data in different ways when you generate reports. You establish a relationship between a variable value and metadata related to that value. Classifications can be used on most custom dimensions, such as Tracking code, props, and eVars.
Adobe offers multiple ways to classify data. All classification data operates the same in reporting, and you can combine any of these methods that best fit your organization. Adobe recommends using Classification sets.
A single dimension can have multiple classification dimensions. For example, you can classify Product IDs with additional product attributes, such as product name, color, size, description, and SKU. Each of these attributes would be a separate classification dimension belonging to the same parent dimension. Augmenting your reports with these attributes provides deeper and more complex reporting opportunities. Once a dimension contains classification data, the classification dimension is available in reporting that contains only classification dimension items. Any parent dimension item that does not contain a classification value is grouped under Unspecified