Files with the extension MHT are used by Internet Explorer to save a Web page as a single file. MHT files can also be created and viewed by other browsers after installing extensions or changing settings. Though useful for saving a page, there is no standard for creating these files, so MHT files created with one browser may not display correctly in another browser. MHT files do not save images, only links to the online images, so if the online images are moved, deleted or renamed, they will not appear when the MHT file is opened.
Internet Explorer natively supports creating and opening MHT files. Using MHT files in Chrome is not supported but can be done by going to the Experiments page (chrome://flags) and turning on "Save Page as MHTML." MHTML is short for Mime HTML, the name for files stored in the MHT format. Firefox and other browsers require an extension or add-on. To avoid installing malicious software, search for add-ons within the browser or at the browser's support site, using the term MHT or MHTML. MHT files can also be opened in Microsoft Office programs such as Word.
If you double click an MHT file and get the error "Windows can't open this file," you need to associate the file type with a program. Choose "Select a program from a list of installed programs," click "OK," then choose a browser, preferably Internet Explorer or Microsoft Word.
Additionally, Microsoft Support reports a known issue in which an MHT file link in an Office document will not open; you may need to edit the Windows Registry to solve the issue (see Resources).