[tech_vaibhav_ee]

how do we give a digital 1 or 0 to a wire..(does giving a wire 5v makes it digitally 1 and giving 0v makes it digitally 0??)
suppose i have four input wires connected to a microcontroller giving following inputs:
1st wire : 5volt
2nd wire : 0 volt
3rd wire : 3 volt
4th wire : -3 volts
are these inputs analog or digital??
if they are analog then how do we give a digital input??
if they are digital inputs then which of them would be 1 and which would be zero??
please do not ignore my question thinking it to be too basic!!! i have searched from winki..to google to get my answer but couldnt get it...
thanks!!!