What is required to summarize data using the 'Group by' feature?

To summarize data using the 'Group by' feature, specifying which fields to group by is essential. This functionality allows users to organize data entries into categories based on the values of specific fields. When you choose a particular field to group by, the data set is aggregated accordingly, enabling you to analyze patterns and trends more effectively.

For instance, if you are summarizing sales data, grouping by the sales representative field would allow you to see total sales by each representative rather than as a singular total. This insight is vital for understanding performance at a more granular level.

In contrast, requirements such as having multiple data sources linked or generating reports ahead of time are not necessary for using the 'Group by' feature, as the feature can operate with a single data source and does not depend on pre-generated reports. Additionally, while applying filters might be beneficial for refining the data you wish to examine, it is not a prerequisite for the grouping process itself. Thus, specifying which fields to group by is the fundamental requirement to effectively utilize this feature.