This chapter is from the book
Installing Apache on Mac OS X
Lucky you, Apache is already installed on Mac OS X! By default, the Apache server binary is located at /usr/sbin/httpd. Configuration files such as httpd.conf, the master configuration file for Apache, are found in /etc/httpd. Because Apache is ready to go (and is fully prepared to use PHP), skip ahead to the "Apache Configuration File Structure" section to learn about the Apache configuration file and how to use it.