Saving Your Web Page
You create Web pages with a text editor, but they are meant to be viewed with multiple browsers on multiple platforms. To be accessible to all of these different programs, you save Web pages in a universal “text only” format—without any of the proprietary formatting that a word processor might apply.
So that browsers (and servers) recognize Web pages and know to interpret the markup they contain, Web page files have the .html or .htm extension in their file names; this also distinguishes these files from plain text files that are not Web pages. Although both work, it’s customary to use the .html extension, so I recommend you use it for your files.
Because of that extension, a Web page’s icon matches the system’s default browser—not ...