What is a parked domain? Well, it’s an undeveloped webpage belonging to a domain name registrar or domain name holder; in other words, is a single page that show only advertising [PPC (pay per click)] related to the topic of the research that you made on the web.
From google AdWords Help Center: Now, parked domain sites offer ads that can be relevant to a user's search query. Some parked domain sites also include a search box, which allows users to further refine their search. Depending on the design of the site, a parked domain site will be classified as either a search site or a content site. That means your ads may show on parked domain sites if your campaign is opted in to the search or content networks.
What's this mean?
If you have a parked domain (many hosting service allow to open a various number of parked domain) make money with ads is pretty simple and more profitable than with a developed website. That’s because is intuitive that the visitors will probably click on the ads for absence of other contents, and most of all because the ads are agreeing with the main visitor’s research.
3 Parked Domains host service:
Example of parked domain: blogtelecast.com