Guided = Physical path like ethernet or a cable Unguided = Radio waves like WiFi
Baud rate is the number of signal updates per second Voltage levels are the number of voltages recorded in the signal not including 0V the more voltage levels, the more bits required.
bits per signal = 2 to the power of: bits available for each signal
increase bit rate -> increase bandwidth -> increase number of voltage levels
2 bits/signal 10 signals/second bitrate = bits/second = 2x10 = 20 bits/second
bit rate = bits per second baud rate = signal changes per second
bit rate = baud rate X bits per second
bandwidth = range of frequencies available.
Serial - singe piece of wire parallel - 2 wires simultaneously transmit data. 2 bits at a time. can be different bits as they are not mirrored skew - the deference between the 2 parallel cables.