How can I easily check if an object is linked to an other object? Sometimes I accidently make changes to an object without noticing that it is still linked to another object.
Is there a simple way to keep an eye on object links?

I couldn't find it anywhere in the properties section or in the outliner.
Right now I usually enter edit mode, zoom out and look around to see if any other object also switched to edit mode. But this method is quiet clumsy and sometimes I forget to do that and miss the link.
I just found the answer for my question myself:

In the properties panel I have to go to the object data section. If a number is displayed beside the mesh-icon it means that the mesh of the selected object is linked to at least one other object: