Notes
Tabular:
This is the simplest of reports and is suited just to show lines of data and nothing else. It is similar to an Excel spreadsheet. If you just want to show data without the need to show totals, calculations or groups of data, then this is the report for you. It is also best to use this report type if you are planning to export data.
Summary:
As soon as you add a grouping, you will turn the report into a summary report. Summary reports are probably the most commonly used and are great for showing groups of data, e.g., if you want to see the number or value of opportunities per account, you would group your report by Account Name. You can also subgroup fields by dragging them under the initial group.
Matrix:
Matrix reports are very similar to a summary, but they allow you to group by rows as well as columns to see different totals. Building on the example above, you might want to see the value of opportunities per account, by month. So you would see that Edge Communications has $100,000 of opportunities in January, $50,000 in February and so on.
Joined Reports:
Joined reports allow you to create two separate reports so that you can compare data. You could use a Joined report to show the total number of opportunities and cases per account, side by side.