/etc/nginx/sites-enabled/default

After installing nginx with apt, /etc/nginx/sites-enabled/default is a symbolic link to /etc/nginx/sites-available/default.

Typically, /etc/nginx/nginx.conf contains the directive include /etc/nginx/modules-enabled/*.conf;. So, the nginx administrator can remove the symbolic link from the /etc/nginx/sites-enabled directory so that the default configuration is not read anymore.

The default file in /etc/nginx/sites-available is then left untouched so that it will still reflect updates by the nginx updating team.