Short answer
NAP consistency means a business publishes exactly the same name, address and phone number everywhere it appears online — its own site, its business profile, directories, and social pages. Discrepancies split the evidence for a single business across several partly-matching records.
Also called: Name, Address, Phone consistency, Citation consistency
The failure is rarely dramatic. It is an abbreviated street type in one listing, an old mobile number in another, a trading name on a third. Each looks harmless; together they weaken the match confidence that local ranking and AI-answer sourcing depend on.
The fix is procedural rather than technical: write the canonical form down once, use it verbatim on every submission, and audit existing listings against it before creating new ones.
Related terms
Local SEO
Local SEO is optimisation for searches with geographic intent — queries naming a city, or carrying implicit "near me" intent.
Entity SEO
Entity SEO is the practice of making a search engine resolve a business, person or product as one distinct thing rather than a set of unconnected mentions.
Google Business Profile (GBP)
A Google Business Profile is the free listing that determines whether a business appears in Google Maps and the local map results, and what shows in its knowledge panel.
Reading definitions because you are scoping a project? Skip ahead and just ask.