When you publish an Excel workbook or worksheet as a Web page, Excel creates a supporting folder named "filename_ files" where it saves all the page's supporting files
When you delete elements that were saved as relative links, Excel automatically deletes the corresponding supporting files from the supporting folder.
If you move or copy your Web page to another location, you must also move the supporting folder so that you maintain all links to your Web page. When you republish to another location, Excel automatically copies the supporting folder for you.
For example, suppose you have a Web page: http://example.microsoft.com/Page1.htm. It includes bullets, which are stored in a supporting folder: http://example.microsoft.com/Page1_ files. The relative paths for the bullet files are /Page1_ files/image001.gif and /Page1_ files/image002.gif. If you move Page1.htm to a new location, such as http://example.microsoft.com/, you must also move the supporting files folder (Page1_ files) to http://example.microsoft.com/.
By default, the name of the supporting folder is the name of the Web page plus an underscore (_) or a hyphen (-), and the word "files." The word "files" will appear in the language of the version of Excel used to save the file as a Web page. For example, suppose you use the Dutch language version of Excel to save a file called Page1 as a Web page. The default name of the supporting folder would be Page1_ bestanden.
Relative and absolute hyperlinks
When you create Web pages, Microsoft Excel automatically manages the related files and hyperlinks so that the images appear and the links work when the pages are placed on the final Web server.
When all the files
Hyperlinks to Web sites on other servers
When you save your Web pages to a different location, links that can't be converted to relative links remain as absolute links.