On-page SEO divides into five operational categories, though they overlap in practice. Content optimization covers keyword placement, topical depth, semantic relevance, and media integration—basically everything visitors consume. HTML and structural elements include title tags, meta descriptions, header hierarchy (H1–H6), schema markup, and image alt attributes that signal page meaning to crawlers. Internal linking manages how equity flows between your pages through anchor text, contextual relevance, and site architecture. User experience signals encompass mobile responsiveness, readability, layout shift stability, and engagement hooks that reduce pogo-sticking. Page speed and technical performance address render time, Core Web Vitals, resource compression, and code bloat that affect crawl budget and ranking thresholds. Some frameworks split this differently. Google's own documentation emphasizes E-E-A-T (experience, expertise, authoritativeness, trust) as a content-layer consideration, while others separate mobile optimization or accessibility into standalone buckets. At Ottawa SEO, we don't treat these as silos—fixing page speed often improves UX signals, and better content structure strengthens internal linking opportunities. The practical priority depends on your baseline. A brand-new page needs solid HTML markup and content first. An established page underperforming in position 6–10 often benefits more from UX refinements or internal link reinforcement than rewriting content. E-commerce pages weight schema and speed heavily because conversion friction kills rankings indirectly through behavioral metrics. Local service pages need geo-specific content optimization and structured data for map pack eligibility. What matters more than counting types is auditing which layer is your bottleneck. We've seen Ottawa clients stuck at position 12 purely because their title tags were generic, and others with perfect technical scores but thin content that never moved. On-page SEO is the foundation—off-page authority and technical health matter, but you can't rank a poorly optimized page through links alone anymore. Start with content and HTML structure, then layer in UX and speed as you scale.