I am trying to use places api for google map on my website. As the manual (http://code.google.com/apis/maps/documentation/places/) says it needs registration and the registration needs adsense publisher id. What is the point why should I have adsense to use maps?
That document says
Additionally, calculation of Place information may generate ... advertising which must be displayed to the user in some fashion.
and maybe that's served to you through AdSense. But it seems odd to me, yes.
In places API of the Google map you are indirectly advertising for that place. Also, that place appears the search of google local business search.
So that may be Googles view for getting the adsense. As google is also doing business. That might be there strategy to generate revenue or future business plan.
来源：https://stackoverflow.com/questions/3448687/google-maps-places-api-why-do-they-need-adsense-publisher-id