301: 301 is an HTTP response status code that indicates a file has been permanently moved to another location.
For many webmasters and internet experts, 301 is the preferred method to redirect users to new websites or page locations. More ranking data is passed to your page then with other redirect options, so it's usually the preferred method.
Even Google recently updated its webmaster guidelines to recommend 301 redirects. Previously, the search engine provider had recommended 302 redirects, but they can be difficult for search engines to navigate and are used more often for temporary changes. Google also recommends using a 301 redirect to alter the URL that appears in search results.
301 redirects are useful if you're trying to make a fairly smooth and seamless transition to a new domain, or if you're merging two websites together and want to make sure old URLs are still getting users to the right pages. You can also use it if your clients use several different URLs to access your domain. A 301 would direct the visits to your preferred domain.
In order to implement a 301 redirect, you'll usually need access to your host server. The process differs from provider to provider so it's best to consult your host before you take action.