ReSharper 8.0 Web Help

It's essential and important to navigate up and down symbol inheritance hierarchy. You can not only move from the current symbol to its declaration or navigate to usages, for example, but also gain some insight into symbol inheritance and type dependencies within you solution.

So Navigating from Symbols is a set of features that helps you:

The scope of navigation is not limited to files in your solution. You can also navigate to types from referenced libraries.