Which feature allows you to upload a CSV file containing item data to join with Google Analytics data?

The feature that allows you to upload a CSV file containing item data to join with Google Analytics data is known as data import. This functionality is particularly useful for enriching your existing Google Analytics data with additional information that you have outside of Google Analytics, such as product details, costs, or inventory levels. By using data import, you can consolidate vast amounts of data from various sources, which helps in better analysis and reporting.

Data import allows you to update existing data, add new dimensions, or include metrics that aren’t tracked by default. This enhances the context of your website or app usage data by providing additional insights that can lead to more informed decisions.

The other options do involve data handling in Google Analytics but serve different purposes. Measurement Protocol is used to send data directly to Google Analytics servers, typically for tracking offline events or interactions. Custom definitions are created to define custom dimensions and metrics for deeper analysis but do not involve uploading data files. Event tracking focuses on capturing specific interactions on the website or app but does not provide the functionality to upload CSV files.