Let's say, you do a Search in the Essence Portal. Next you click one item from the list of results and you can see the details. If then you notice you clicked the wrong item, you can click the Back button from the browser to return to the Search screen. But if you wanted to go back to click on of the other items from the result, than you will have to enter the Search criteria again and perform the same Search. The easiest and fastest way then is to click the Use the last Search option.
But there is an easier and faster way
Instead of using the Back button from the browser, you can go back to the Search in 2 other ways. You can click the GoBack button, and you will go back to the Search screen using the last Search criteria and the Search will be automatically be executed. It's like going back to the Search results, though keep in mind it is a fresh result set.
Or you can click the Entity Name at the top of the page, and that will bring you back to the Search page using the default Search Criteria. It's like clicking the Back button in your browser.