This will apply to Maps, Books and Podcast apps. Apple has started testing search ads in Maps. Restaurants, shops etc. Recommendations for it will be shown here.
Apple already implements a similar advertising model in the App Store: developers can pay to promote their apps on the search page for a specific query, such as “puzzles” or “photo editor”. As Gurman points out, Maps ads can work the same way: Companies will pay to appear at the top of search results.
Source: Ferra
