how does X10 home automation work, technically?

how does the remote signal get to the devices? what type of signal does it use? what is the best way of setting it up.

Thanks for your question. It made me go look for an interesting article. http://en.wikipedia.org/wiki/X10_%28industry_standard%29
X10 sends a carrier signal over the mains network. It modulates the mains electricity (doing no harm to anything while it does) into a signal that other X10 receivers listen for and understand... In its simplist form thats how it works...