copy one textbox text into other textbox in other page

Hi

I have 2 page index.aspx page and search.aspx

in index.aspx I have 1 textbox==txtIndex and 1 button ==btnIndex

and in search.aspx page I have 1 TB==txtsearch  and 1Button==btnsearch

I want when users enter text into TxtIndex that is in Index.aspx page and click on btnIndex

It go to Search.aspx and copy txtIndex.Text into TxtSearch

How I can do It?

Thanks alot