A 301 redirect is a permanent redirect from one URL to another. It is a technique used in SEO to ensure that when a user or search engine visits a specific URL, they are automatically redirected to a different URL. This is commonly done when a website undergoes a redesign, changes its domain name, or consolidates multiple pages into one. The 301 redirect helps preserve the SEO value of the original URL by transferring it to the new URL, ensuring that users and search engines can still access the desired content.