Apache

Apache is a free Web server, that according to a Netcraft Web server survey, powers more than 60% of all Web sites on the Internet. Apache runs on most operating systems including Linux, Windows, Solaris, Digital UNIX, AmigaOS, etc.
www.httpd.apache.org

Disable directory index 📁 on Apache

When Apache Directory Index is enabled, if you browse to a url that have no index file present, you will see list of all files. This is not good for securiy as hackers can see all files present in the directory.