Modals allows the user to view almost any content in pop-up Windows, but the free version of this extension does not operate some features, such as: Modal Content Tag, Positioning, Groups / Slideshows and many other useful items.
Full control over the CSS style.
The sizing of the window.
Easily create pop-up Windows.
To understand how the insertion of such an element on the page, you need only remember a simple code:
In addition to the main tag, there are others, with which you will be able not only to open an external link to another site, but and use PDF documents in the internal window, and any images and galleries.
Thus, you have the opportunity to insert anything from links to whole documents.