Short definition
Google Business Profile is the free Google listing that controls how a business appears in Google Search, Google Maps, and the local map pack.
In depth
Formerly Google My Business, GBP is the single highest-ROI asset for any local service business. A well-optimized GBP — accurate categories, complete services, fresh photos, weekly posts, answered Q&A, ongoing review collection — wins map-pack placements that produce calls without ads. GBP is also a primary source for AI engines answering 'best [service] in [city]' queries; Perplexity and ChatGPT frequently cite GBP-sourced reviews and hours.
Example
A plumber updates GBP categories from 'Plumber' to add 'Drainage service' and 'Water heater repair', posts weekly photos of jobs, and earns 14 new reviews. Map-pack impressions jump 220%.