NAP (Name, Address, Phone)
NAP refers to the business name, address, and phone number triple. Strict consistency — down to the character — across the website, Google listing, and directories determines how much trust search engines place in the establishment’s physical existence.
In practice
A minor variation — 'blvd' here, 'boulevard' there, an old number still sitting on a directory — creates competing entities in the algorithm’s view. The remediation process begins with an inventory of existing citations, then corrects them one by one. Tedious work, but among the few local SEO tasks with near-mechanical results.