What is a tfm file and how do I open a tfm file?
When typesetting Tex and Latex document fonts, the font files that are created through this process are called TFM files. These are files representing Tex font metric differentiating it from TrueType. Font glyphs are not contained in these files because glyphs are saved using PFM and AFM types at a different location. Instead, these TFM files contain the information of the glyphs such as the height and the weight. TFM files are necessary for typesetting Tex and also typset a font from a separate file into Tex file. Since these files contain necessary formation about the glyphs, the creation of TeX's DVI output is possible. TFM files are smaller and compact in size and they can either be generated from TrueType or Adobe Font Metric wherein these programs belong to most bundles of Tex and Latex. The font format known as MF is also used with TFM fles. TFM files can be opened using applications such as TeXworks, MiKTeX,and TeXworks.
Relevant tfm file links:
How to open tfm file on YoutubeHow to open tfm file on Wikipedia
How to open tfm file on Microsoft.com