A page can be technically live, in the sitemap, and indexed — and still be orphaned. Without internal links, search engines and users have no contextual signal about the page's importance, topical neighbourhood, or relationship to the rest of the site.
Orphans are usually accidental: a blog post written for a campaign and never re-linked, a product page imported from a migration, an old landing page that lost its inbound link when a layout changed. They accumulate silently.
The fix is identification followed by deliberate linking: crawl your site, find pages with zero inbound internal links, and add 2–3 contextual links from related published pages. Done at scale, this is one of the highest-ROI SEO interventions on most sites.