What is the purpose of the 'Group By' operation in Power Query?

The 'Group By' operation in Power Query serves the primary function of summarizing data by aggregating it based on specified columns. When you apply 'Group By', you can consolidate rows of data into single rows that represent summaries. This operation allows you to perform calculations such as sums, averages, counts, and more on the data that share common characteristics defined by the grouping columns.

For example, if you have sales data for different products and want to know the total sales amount for each product, the 'Group By' feature would allow you to group all records by the product and then sum the sales figures for each group. This capability enhances data analysis by enabling users to derive meaningful insights from large datasets and allows for clearer reporting and visualization of key statistics.

The other options relate to different functions in data processing: formatting data for visualization pertains to adjusting how data is presented, filtering is focused on excluding data that does not meet certain criteria, and joining datasets involves combining multiple tables based on common fields.