The /bin folder
Contains various binarie:
httpd
This is the server binary itself
apachectl
This controlls the server (start, stop, restart)
htpasswd
This creates user data for Apache passworded directories.
ab
This is used for benchmarking
apxs
Apache extension tool: this is used for expanding apache by compiling new modules.
rotatelogs
This is used for rotating the Apache logs.
The /conf directory
This folder contains configuration files, mainly httpd.conf.
The /modules folder
This contains DSO modules (Dynamic Shared Objects) – binaries that are dynamicaly loaded at server startup.