While modeling or any kind of scene design you may come to the point to duplicate an object to place it a multiple amount of time. Linked objects are as well a very good option when you want to continue working on one object and influence all duplicates too.
This video is only for the 'Duplicate' Function. I know that there is as well the Ctrl+C and Ctrl+V shortcut for duplication. But I want to focus only on the duplicate function itself (as it is implemented in Blender).