Can includes be done in just regular .htm pages?

[Dravyk]

Server Side Includes (SSI) use CGI includes and most go to pages labeled .shtml

You can also do virtual includes using PHP, and they have to be called out on pages ending in .php

However, you can also have your server set up by your host (if they're amenable to it) to have your .shtml pages actually end in just .html (but really be .shtml). I am told you can also do this with PHP, however no host will do both because then it causes too much server drag to parse for both.