It can mark important phrases in website pages, similar to manually color marking on paper.

It is a program, with which you can do some marking and basic editing of MHT files. MHT files are files containing complete website pages; they include images and other elements of the page. MHT files normally are created with Internet Explorer (IE). This program -eMarker- can open a MHT file, go into edit mode letting the user format text parts like making bold or underline and giving a background color (=color marking!). Then this can be saved back into the MHT file.
Similarly you can edit htm(l) and even eml-files.
It is especially made for professional users who can win a lot of time and money using this technique.
For instance for applications in the financial world: you can save lots of complete web pages concerning a certain firm or share and indicate only the most important parts in them. This way you keep your overview and can act more quickly and more correctly.