MHTML, sometimes referred as MHT, stands for MIME HTML is a single file in which entire webpage is archived. When one saves a webpage as MHTML format, this file extension will contain HTML code, images, audio files, flash animation etc.

• MHTML (Multipurpose Internet Mail Extension HTML) file format is also known as web page achive format.
• Not only is the file contains html code for web page but also all the sub-resources (such as images, Java applets, audio files, Flash animation).
• Internet Explorer and Opera support this file by default
• In order to save webpage as MHTML file extension in Mozilla Firefox, users need to install an add-on, named Mozilla Archive Format and another one is UnMHT.
• To archive a webpage as MHT/MHTML in Chrome browser, you need to enter chrome://flags/ in the URL field. Then scroll down, go to Save as MHTML option and select Enable.

The MHT/MHTML file belongs to the category of Web Files.

The following applications create and open MHT/MHTML files.

• multipart/related
• application/x-mimearchive
• message/rfc822

hex: 46 72 6F 6D 3A 20 3C

The MHT/MHTML file can be opened using Google Chrome, Mozilla Firefox, Safari and more. The internal structure or data inside MHTML file can be seen using any text editor like Notepad++, Atom and more.