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?

>>8
Read the technical specs for the chip you are trying to extract firmware from and learn about JTAG debug points.  Also graduate from an 8-year EE program first.  Thanks!