There is some news aggregator sites like :
http://domain.com/ **link removed
Sorry, The website is in persian language. But the main purpose is the same . This website is using drupal as their CMS . they get the news from other news websites and aggregate them.
As you can see, They do not copy the entire article, They just copy the excerpts and featured images, Then , When you click on the permalink of the news , The original news source website will show up using an Iframe, But still you are in the first website.
How they do this ? Is there any Drupal module which can do the same ?
Mostafa there is not a Drupal module that currently does this.
You can, however, use the feeds module to import a summary of the content, then using views template, perhaps write a bit of code to (onclick) load the url in an iframe.
This is where I'd start.