Imagine you have long list of data and you need to quickly identify which of the items are unique. You can use Advanced Filters to do this.
Just select the list of items you want to filter, go to menu > Data > Filter > Advanced filter. You will see a dialog box like this:
Thats all, when you click ok you will see unique items of the selected list. Quick, aint it?
If you want to see all items, go to menu > Data > Filter > show all.