One of the most used pages when doing any technical discussions on SharePoint governance is the great SharePoint 2010 Capacity Management: Software boundaries and Limits on TechNet.
If you every have any questions from users about can we do this? What if I uploaded this? Does SharePoint support this? I recommend before you answer you take a quick look at this page to get an up to date view on what is/isn’t supported and guidelines for good practice.
The page covers
- Boundaries: Static limits that cannot be exceeded by design
- Thresholds: Configurable limits that can be exceeded to accommodate specific requirements
- Supported limits: Configurable limits that have been set by default to a tested value
One thing to also consider is what is referred to as the Equalizer metaphor, the impact that some values have on others. Take your time, read the article and bookmark it for future reference.