Extracting Firmware or Bios

I don`t know where other place to ask so here`s the place.
I read in the news bout hardware hacking such as Bios and the Firmware hacking. And i'm curious just how exactly do we extract the firmware information ? I mean it`s ll embeded into a rom chip right so how the hell we extract it?

Something tells me you really shouldn't be fucking around with your firmware.
Don't forget, it voids your warranty, so the nice people at Dell won't help you out when you break it.