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
Dealing with files on MDN