Return to Search result page

I stuck with Problem where i have to return to previous page with out posting it back to server, Like gmail, where we can search for an email which list the bunch of emails and you open one and then click "back to results" button and you are back to search results page without server postback. I honestly dont have any idea how does this work, but if anybody could guide me the right path, would be great. When i was googling i came across few techniques like 1. Caching the particular page 2. simulate the browsers back button (it cause post back for me)

If the explanation with ASP.NET context would be great.