Reports can summarize and group data to give an overview.
Reports are often used to present a big-picture overview, highlighting main facts and trends.
Grouping data and sorting data to make it more visibly meaningful are key benefits of reports. Reports let people take in the big picture at a glance.
So a sales report might group sales by region, by salesperson, and by quarter, showing subtotals as well as a grand total. A club newsletter could show how many people have been members for 5, 10, or 20 years; report meeting attendance by month and overall; and list how many members live in which cities.
Although reports enable you to dress your data for success, grouping and presenting data in many different ways, they don't alter the underlying data in the tables in your database.