RE: How does YLO protect their data?I'll draw an analogy.
If you get a phone book delivered to your door, and would like to make your own copy of the phone book, you can go to the library with a big wad of cash, start photocopying away, and several hours later, you can have your own copy of the phone book. Then, you can take that phone book, call it the trendy pages, and make thousands of copies to drop off at everyone's porch. Nobody has paid you to do this and you may get sued, but overall all that's happened is that you've done some free advertising for someone. However, nobody will know what trendy pages are all about. When a business listing in the phone book changes, you won't know about it unless you're watching constantly and recopying the book over and over. Still, nobody is paying you to do this.
Copying online is simpler, logistically -- it's called web scraping and it takes a static copy of an entire website, following all the links. However, the copied website is still a static copy. It doesn't have history behind it, so it doesn't have that PR8 rank on google that yellow pages has, and if the source information changes, the site needs to be re-copied. There is a difference between your copied site and the source site because the source site is being displayed based on a database that YPG is updating regularly based on sales/customer service interaction. Conversely, the copy site is a static copy. You could arguably keep synchronizing your copy with the YPG site but eventually this activitity would be detected and blocked by the YPG webmasters.
Again, you can get sued for duplicating a directory and calling it your own. Moreover, there is no money to be made since it's the paid ads that bring in your revenue. The information that would be copied is information that's public anyway (it's on public, advertising website called yellowpages.ca).
If this was the gist of the kind of copying you were referring to, that's the answer.
Another way you might want to copy the YPG website is if you're a cell phone app developer and you want your own cell phone application instead of YPG's. In this scenario, communication between YPG database and the cellphone application is via a secured channel called an API. A third party can't tap into that channel unless they have been granted access by YPG.
Finally, the YPG website has a public area and private one. The private one is where advertisers have information that they don't want to share with the world (e.g. information about their account, private contact details, etc). This area of the website is placed behind a login and is typically on a secured URL (https versus http). This area cannot be copied in much the same way that one's online banking account cannot be accessed by the general public.
Hope this helps. Your question was a bit general so I missed the point, let me know.
Mark