301 Redirect – A 301 redirect automatically causes one url to redirect to another and tells the Web (and search engines) that this redirect is permanent, as opposed to a temporary (302) redirect. 301 redirects are generally preferable for Search Engine Optimization purposes and are therefore often referred to as search engine friendly redirects.
A 301 Redirect allows a website owner to create a new content page that contains updated information and/or an improved user interface without losing established position on a search engine. When people conduct a search the 301 Redirect code tells the search engine to take people to the new page instead of the old one.
The advantage is that all the time and effort that went into establishing the old page in search results will be applied to the new page instantly. Without using a 301 Redirect the new page would have to once again establish itself in search results over time.
Search engines will automatically direct users to the new page and eventually associate the new page with search inputs, completely bypassing the old page altogether.
This is a very simple and effective strategy that allows website developers to set up new pages and maintain Search Engine Optimization (SEO).