Today you’ll see a new and improved sitelinks search box. When shown, it will make it easier for users to reach specific content on your site, directly through your own site-search pages.
What’s this search box and when does it appear for my site? What’s this search box and when does it appear for my site?
For more details Visit: http://googlewebmastercentral.blogspot.in/2014/09/improved-sitelinks-search-box.html