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Redirection 301

A 301 redirect is a server response issued by web servers, when it is asked for a particular URL which has been shifted to a new location permanently.

This is what happens:  

Browser to server: Send me page1

Server to browser: 301, page2

Browser to server: Send me page 2

When a search engine crawler gets a 301 response, realizes that page1 has now been permanently replaced by page2. It therefore now starts a process of replacing all instances of page1 in its index with page2. All instances of search results where page1 showed up will be replaced by page2. All value and link juice associated to page1 previously will now be moved to page2.  

There are several methods of creating 301 redirects. On a PHP web server, 301 redirection directives are stored inside the .htaccess file.