Craig Campbell is an SEO consultant based in Glasgow, Scotland with 16 years of experience in the industry. He discusses common SEO mistakes and how to fix them, including performing audits using SEMRush to identify issues like crawlability, errors, and warnings. Campbell also covers how to improve site speed by reducing page load times and time to first byte through techniques like trimming page size, enabling browser caching, using a content delivery network like Cloudflare, and updating plugins and files.