When filtering results by context, for what purpose do we use aggregation?

Filtering results by context (using WHERE) narrows down the rows that will be considered for further processing. Aggregation then summarizes those filtered rows into meaningful metrics. For example, you might filter sales records to a specific date range or region, then aggregate to compute total sales, average order value, or count of orders. Aggregation is used to transform detailed data into higher-level insights, such as totals, averages, or counts, which are easier to interpret and report. It allows you to answer business questions like "How many orders were placed in Q1?" or "What is the average revenue per customer in the EU?" by combining filtering to focus on relevant data and aggregation to produce concise summaries.