Apache : Redirect Root URL to Subfolder

Solution :

RewriteEngine on
RewriteCond %{REQUEST_URI} ^/$
RewriteRule (.*) /mysubfolder/ [R=301]

• RewriteEngine on is used to specify to Apache that this site will use Rewrite rules to transform the URL
• RewriteCond is the match part of the pattern. If the URL matches this pattern then RewriteRule will be applied. This particular pattern is checking if the requested URL path is equal to /.
• RewriteRule is going to add /mysubfolder/ to the URL which only contains the domain due to the above RewriteCond already performing the check.

Source: 

• https://www.jamescoyle.net/how-to/1424-apache-redirect-root-url-to-subfolder