A 301 redirect is a permanent redirect from URL to another. Basically, they are important because they are the key to transferring all your old SEO efforts to new URLs. Whether you are consolidating content or switching domain names, this is a crucial step in the process that can’t be overlooked.
Here’s an example. Let’s say your current site has a “Team” page (at yoursite.com/team), as well as a “Culture” page (at yoursite.com/culture). However, as part of your website redesign, you want to consolidate the content from those two pages into a single “About Us” page (at yoursite.com/about). To transfer the SEO authority of those pages to your new page, you’ll want to set up 301 redirects so that yoursite.com/team and yoursite.com/culture both send folks to the new URL, yoursite.com/about.
Forgoing this can result in a drop in your page rankings, as well as leading to a ton of 404 (“Page Not Found”) error messages for your site’s visitors. Many people forget to do this when they are redesigning their sites, creating new pages to replace the old ones. Often what happens is that these old pages or sites might still be ranking in the search engine results or have a ton of backlinks.
If you get rid of them, you end up eliminating all of the SEO value you’ve worked so hard to build. A lot of people don’t realize this until it’s too late and their search engine ranking plummets when they launch their new site.
Fortunately, you don’t have to keep hosting those pages forever. As mentioned above, setting up a 301 redirect will let the search engines know where the new pages are, and the SEO will follow you to your new site.