Before I had production servers to manage I never worried about just restarting Apache to reload the configuration. Now I help manage quite a few of them. I needed a way to restart and reload the Apache configuration without having any website downtime.

That's where a "graceful" restart comes in.

"The USR1 or graceful signal causes the parent process to advise the children to exit after their current request (or to exit immediately if they're not serving anything). The parent re-reads its configuration files and re-opens its log files. As each child dies off the parent replaces it with a child from the new generation of the configuration, which begins serving new requests immediately."

Excellent! Apache reloads the config and moves connections over to the new configuration as it can. You get no down time, and the changes get rolled out right away.

Reference: http://httpd.apache.org/docs/2.0/stopping.html