301 redirects are permanent and are usually used to solve problems with duplicate content, or if URLs are no longer necessary. The old, used URLs might have SEO authority and value that should be transferred to the new URL. This is the most common use of 301 redirects. and it’s good for SEO because 301 redirects will funnel link juice from the old page to the new one. Just make sure you redirect old URLs to the most relevant pages.