Backlink counts and Harmonic Centrality both describe parts of a web graph, but they are not interchangeable. A backlink count usually asks how many links point toward a domain. Harmonic Centrality asks how close that domain is to the other nodes it can reach through directed paths.
What a backlink count captures
A backlink report is commonly centered on inbound links, referring pages, or referring domains. It can be useful for auditing discovery, partnerships, and link acquisition. The result depends on the crawler, its index, duplicate handling, and the definition of a counted link.
What Harmonic Centrality captures
Harmonic Centrality follows directed paths from a node and gives larger contributions to shorter paths. A domain with fewer direct links can still be close to a broad connected region through several short paths. A domain with many inbound links may not have broad outgoing reach in the graph.
Use the measurements together
Compare both metrics inside the same investigation. A gap between backlink volume and Harmonic Centrality can suggest a useful question about link direction, graph coverage, or the kinds of pages represented. It is a prompt for inspection, not a diagnosis of quality or search performance.
Start with the Harmonic Centrality calculator, then read Harmonic Centrality versus PageRank and what Common Crawl includes.