[Dave]

Yes, the child directory can run without its own .htaccess file if it meets the parent .htaccess rules. If you add 3 rules in a .htaccess file in the child directory, it will inherit the parent rules and load the 3 additional rules.

The most popular feature of .htaccess is "RewriteRule" where if a certain condition is met, it redirects either the user or request internally to a different script or page. You can also deny access based on IP addresses like you said. The rewrite rules are commonly used for clean URL's. For example a page at example.com/category/subcategory/productname might rewrite the URL behind the scenes to example.com/index.php?route=category/subcategory/productname where the framework that runs behind the scenes parses the URL and further processes it to show the proper page.

Here is a good source for you https://httpd.apache.org/docs/curren.../htaccess.html