httpd is the Apache Hyper Text Transfer Protocol (HTTP) server program. It is designed to be run as a standalone daemon process. When used like this it will create a pool of child processes or threads to handle requests.
In general, httpd should not be invoked directly, but rather should be invoked via apachectl on Unix-based systems.
The httpd RPM package provides the /usr/sbin/httpd daemon and its configuration files.
/sbin/service httpd show
Usage: httpd {start|stop|restart|condrestart|reload|status|fullstatus|graceful|help|configtest}
/etc/httpd/conf/httpd.conf