Summary Fields make it easier to search for contacts (or insert tokens) based on a summary or other calculation of the contact's previous interactions.
For example, you can access a contact's total lifetime contribution amount, last membership contribution date, number of attended events, total of last year's deductible contributions, and more.
Summary Fields extends your CiviCRM data by creating a tab of fields that total up and summarize the fields you choose.
Once you've completed set-up, a new tab will appear alongside the other tabs in contact records showing the totals for each individual. The fields in this tab will appears in Advanced Search and will be available as tokens for emails or PDF merges.
After installing the extension, you must configure it before any summary fields are calculated.
You can configure the extension by going to Adminster -> Customize Data and Screens -> Summary Fields.
Choose the fields you want to enable. Every field you enable will slow down the performance of your database just a little, so only enable fields you really need. You can always come back and enable additional fields later.
In addition, you can configure how Summary Fields works. For example, you can choose which financial types should be included when calculating contribution amounts. And you can dedide which participant status types should be considered "attended" and which should be a considered a "no-show".
Do you want more summary fields? Check out Joinery's More Summary Fields for an extension providing yet more fields.
Want still more fields?
You can write your own extension. Learn how in the document DEVELOPERS.md in the this extension.