The .MHT file format was first introduced in 1999 by Microsoft's Internet Explorer web-browser. The .MHT extension stands for MIME HTML and is used for storing web pages and their content (I.E images, audio) in a single file.

Windows 7 uses the .MHT extension with the 'Problem Steps Recorder' tool, an application for recording your screen which can then be used to resolve problems. These .MHT archives contain a collection of images of each step.

The format is not standard and may render differently in different browsers.