Summarized Data

Hi,

I'm working in an environment using SSIM...Can anyone give me a good in depth overview of what Summarized data is, how it works and what it does... Basically anything about Summarized data wil help me alot..

All I know about it is that, summarized data indicates grouped events of a similar nature that have been compressed...

This is good but doesn't actually help me too much.

Thank you.