How To: Save Web Sites Offline

Saving just a page, even with images, is easy. (I'll get to saving a whole site in a moment.) In Firefox, for example, you select File**Save Page As. In the ‘Save as type' field, select Web Page, complete, then save the file. Firefox will save the page as an HTML file, but will also save all the supporting files in a local folder.
Even this doesn't work perfectly, however. Complex formatting may not get properly reproduced.
I recommend HTTrack for saving an entire site. This free program will save all the pages within a domain, including images, while maintaining the link structure. It does not save the pages from external links like those in advertising.