A 301 Redirect is a command carried out by web servers (eg. Apache, IIS etc) which redirects browsers requesting a certain url to another url. A common reason to set up a 301 redirect is when the url of a page has been changed. In order to ensure that the internal and external links to the original url continue to bring visitors to the original page, a 301 redirect is set up and the web server redirects traffic from the old url to the new url. According to John Mueller from Google, a 301 redirect will pass on the PageRank to the new url.