Google started displaying ads Thursday within its local maps as the online search leader tries to find more ways to make money from the free services it has been introducing.

Google already displays some text-based ads to the side of maps. The new ads will show up as part of balloons that float over the map itself and will also carry a small image — a hotel, for instance, can display a tiny shot of its pool.

The new ads will appear only if a search request mentions a product, service or specific business name, said Dominic Preuss, a company product manager for local advertising.

Google doesn’t plan to display the ads when a user is looking up an address or searching for driving directions, Preuss said.

Ads targeted to search queries generate virtually all of Google’s revenue. Besides enriching Google, the system has been a boon for advertisers, whose sales have been boosted by an increased traffic from prospective buyers.