Topic clustering means grouping related pages under a central theme. Internal links are the glue that holds this structure together. For law firms, clusters may include personal injury, criminal defense, or family law. Within each cluster, link subtopics like car accidents or child custody. This forms a web of content that signals authority and coverage. Search engines rank sites higher when they detect structured topic depth. Internal linking helps define those relationships. Without it, clusters appear fragmented and weak. Topic clusters also improve navigation and session duration for visitors.