The file extension for HTML files is
.html. To create a new HTML file in your text editor, create a new file and then save it. In the dialog that pops up, give it a name and add the
.html file extension at the end.
The home page for your website is usually given the name of
index.html. Other HTML files for a website can have more descriptive names, like
If your file name needs to contain multiple words, use hyphens to separate the words, like
Using your text editor, try creating two or three HTML files. Give them different names using the naming conventions described in the Details section.
Dealing with files on MDN