Internal linking is absolutely on-page SEO. You implement it in the page markup, control every attribute, and decide which pages to elevate through strategic anchor text and placement. That makes it on-page by definition, even though its effects ripple across your entire site architecture. Internal links serve three main functions. First, they distribute PageRank throughout your domain, funneling authority from high-traffic pages to conversion or ranking targets. Second, they establish topical relationships through contextual anchor text, signaling to Google which pages cover related concepts. Third, they guide crawlers to discover and index deeper pages that might otherwise sit orphaned in your site structure. The distinction people sometimes draw between on-page and site-wide factors is arbitrary here. A link in your content is as on-page as your title tag. A link in your footer template affects multiple pages, but you still control it at the template level, which is on-page work. The placement matters for impact: contextual links in the main content carry more weight than sidebar or footer links, and links higher in the DOM typically pass more value. At Ottawa SEO, we audit internal linking during every technical SEO engagement because most sites underutilize it. Common mistakes include using generic anchor text like "click here," linking only from navigation instead of body content, and failing to link to commercial pages from relevant informational posts. We typically see 15–40% ranking improvements on target pages just from restructuring internal links and anchor distribution, especially in the 500+ domain portfolio where cross-domain strategy compounds the effect. Watch your anchor text diversity. Over-optimizing exact-match anchors internally looks unnatural, even though it's technically safer than external over-optimization. Aim for a mix of branded, partial-match, and contextual phrases. Also ensure your most important pages sit no more than three clicks from the homepage, which helps both crawl efficiency and user navigation.