What is Monoblock/Dual Mono/Bi-wiring?


I am really new to this beautiful yet confusing world of Hi-Fi audio.

Recently, as I was searaching for an amplifier/pre-amp, I keep running into these words MonoBlocks and Dual Monoblocks and Bi-wiring.
Can anyone kindly explain what they are and if & why they are good for better sound?
sjc0888
Note: "Purest" bi-wiring separates the tweeter from the midrange/woofer whose "backwaves" can corrupt the delicate high frequencies on their way to the tweeter. Some (most?) speakers do include the midrange with the tweeter, however. Make sure to check and see what's-what, when buying speakers, if you plan to bi-amp for bass control, etc...
Thank you guys for your responses.
It's really a big help.
I guess I have a lot to learn.
But it is exciting new world.
Cheers to you all!