An advertiser in Search Ads 360 is first created in Campaign Manager and is the next organizational object in the hierarchy of a virtual Search Ads 360 advertising agency.
A Search Ads 360 agency models an agency structure in that it can contain multiple advertisers. Within each advertiser are usually various engine accounts, such as Google Ads and Bing Ads, that are use to manage and track the effectiveness of search marketing campaigns.
A Search Ads 360 agency is managed by an agency manager which is one of the user types in Search Ads 360. It's up to the agency manager to decide how to organize advertisers and grant different levels of user access to the agency or advertiser. For example, an agency manager might create an advertiser for all the campaigns for a particular client, or maybe create separate advertisers for different product lines or divisions and grant different users access to each of the separate advertisers.
Note that no matter what user type is assigned to a user, only a limited amount of reporting data is available across advertisers. For example, an advertiser user with permission to access more than one advertiser can compare the total number of clicks and cost for each advertiser. However within a single advertiser, an advertiser user can view detailed reporting data, such as metrics for all keywords and ads across all engine accounts and campaigns in that advertiser.