Retrieving a webpage is too difficult. History Search, indexes text on pages you visit. This way you can retrieve any webpage, open online documents, find emails and navigate your web apps using any phrase you remember. How it works is History Search uses browser extensions to index the text on webpages when you visit them. This way you any word you remember will be enough retrieve it for you. So its both technically and literally an index (you know that page in the back of those dusty encyclopaedias).
