A 301 redirect is a permanent way to redirect one URL to another. It tells search engines and browsers that the original page has moved to a new location, ensuring that users and search engines are directed to the correct page. This helps maintain the website's SEO value by transferring link equity from the old URL to the new one. Using a 301 redirect is essential when changing a website's structure, updating content, or moving to a new domain. It prevents broken links and enhances user experience by automatically guiding visitors to the updated page without any extra effort on their part.