Maintain your traffic. If you are redesigning and launching a newer
version of your site – the most effective way to retain search engine
rankings, established backlinks, and PageRank is to use a 301 redirect.
These directives inform search engines the older page has permanently
moved to a new address that’s provided during the redirect
implementation process.
Using a 301 will not damage search result positioning because the search
engines acknowledge the page from the older design has moved and will
keep whatever search engine love intact; this includes PageRank.
Backlinks pointing to the older page will also be salvaged, provided the
301 is implemented correctly – something Google very much endorses.
301 redirects are powerful. Learning to use them correctly is
imperative, especially when you consider the benefits they provide.
For more information on 301 redirects, read more here.