You might have website that redirects to home page when user enters.
Since they all point to same home page many ordinary users and even some developers think these URLs are same.But they have subtle differences from the SEO perspective. This kind of non-canonical URLs can lessen search engine rankings.
From ASP.NET perspective this can be best done with new ASP.NET 4.0 syntax,
rather than Response.Redirect method. Reason for this is
Response.Redirect works by returning a 302 HTTP status code and a
Location HTTP header to the client. Header indicates the URL to which the requested page has been redirected. The 302 status code indicates that the resource being requested has temporarily moved to a new URL like some webmasters do when doing site maintainance tasks. A search engine spider who also acts as client browser that receives a 302 status still use the multiple forms of URLs and index the multiple URL forms.
Solution to this is instead of returning 302 to the browser when doing redirection return status code 301 while doing redirects this has been facilitated in ASP.NET 4 new
Since the status code 301 returned to the client browser but also to search spider it correctly index the pages with canonical home page URL you have decided instead of the multiple URL forms. Which enhances your search engine rankings.