Each time you run a navigation command which changes the selection in the Project Explorer, the element that was previously selected is added to the navigation history. You can access all history elements by pressing the button in the Project Explorer toolbar.
When you click on an element from this list, it will get selected in the Project Explorer. If you want to return to the previously selected element after running a navigation command you can simply press button the toolbar button once. Further clicks on the button navigates to the elements that were selected longer ago (i.e. it works similar to the Back button in a web browser).
The navigation history menu also contains a command “Add Selection to History”. It allows to manually add elements to the navigation history without running any navigation command. This can be useful if you want to quickly bookmark a model element.
Learn more about Model RealTime navigation functionality here.