Broken link building is a method to improve SEO by finding broken links on other websites and offering your own content as a replacement. The process starts by scanning a website to find broken links. Once a broken URL is identified, you prepare relevant content that can replace the broken link. Then, you contact the website owner to suggest replacing the broken link with your content. If the owner accepts, you gain a backlink which helps your SEO. If the owner rejects or ignores the suggestion, the process ends without a backlink. Key points include the importance of finding broken links first, preparing content before outreach, and understanding that the process may not always result in a backlink.