SEO involves optimizing websites to increase traffic from search engines. It has three main parts - technical elements like code quality, content like keywords and descriptions, and links from other credible sites. To improve SEO, websites should use clean code, include keywords in pages and metadata, create sitemaps and internal links, get outside links, and regularly update content. Monitoring tools like Google Analytics and Website Grader help evaluate SEO effectiveness over time. The goal is benchmarking improvements and refining the ongoing SEO process.