SOLIDWORKS has many productive command buried under right click selection. I had prepared a list of such tips and probably would be posting it over here over period of time.

One of that is "Invert Selection". It has been there for long time and we get so much involved in our work that we don't realize its need when stuck. I am showcasing a use case where this could be helpful especially when we are importing geometry or copying sketch from AutoCAD.

When we import geometry which contains surfaces, there are chance that very small faces remains and you might not realize its presence. Your effort solidify fails or you might see that model is so much zoomed out when you are in isometric view. See image below. 
 

When you face such issue: 

1) simply zoom to your 3d model and go in Top View.

2) Select all the surfaces in top view.
 

3) Right click in graphics area and go to "Selection Tools" > "Invert Selection".

4) Now click "Delete" from keyboard and "Delete/keep Body" operation will appear. Since the surface would be existing independently, it would be treated as separate body. "delete Face" won't work.

5) You will see that surface/s will be selected in the property manager. Executed the command and those bodies will be deleted.

Same for sketch entities. Many time you copy large nos. of entities from AutoCAD and there are only few of them which you require. At that point, invert selection helps a lot.

And now since you discovered how invert selection can be useful, it can be helpful in your daily use too!