RZ - return to zero.
NRZ - non-return to zero.
NRZI - non-return to zero invert.
Manchester encoding
Differential Manchester encoding.
Bit stuffing.
Run length Limited
Phase-shift keying.
Frequency-shift keying
Amplitude-shift keying

This data encoding technique uses one voltage level to represent 1 and another to represent 0. This protocol has no neutral level or non-signaling level.

This encoding technique uses a transition in the signal level at the clock time boundry to signal one bit value and a lack of transition to signal the other. Which bit value is represented by a change is specific to a particular implementation. 

This encoding technique uses two different frequencies to represent either zero or one. 

This encoding technique uses an abrupt shift in the carrier's wave form to encode/transmit bits. 

This encoding technique imposes the data on a clock signal. A one is transmitted when the carrier transition is low to high or stays high and a zero when transition is high to low or stays low. There is always a transition change in the middle of the bit transfer to provide clocking. Some bus protocols reverse the low and high assignment. 

This encoding technique imposes the data on a clock signal. It guarentees one transition during a clock period. It will perform an additional clock transition if a one bit is being sent, but no additional transition if zero bit being sent. Some bus protocols reverse the low and high assignment.

This encoding technique encodes a series of sequential bits, usually a byte, in a predefined longer sequence of bits, a symbol, so that the number of sequential 0s or 1s is limited. 

This encoding technique uses two different signal levels to represent zero or one. Additionally, it has an intermediate level that signifies no data transmission.