Transponder car key is any vehicle starting device what includes in it a transponder chip (transponder = transmitter + responder).
This is a security system that disarms the vehicle immobilizer system and allows the ignition to start the engine. Every time you insert the car keys into the ignition switch cylinder and try to turn it on the car computer (ECU = engine control unit) sends an electric pulse to the ignition asking the key to return a pulse back and if the ECU receives the correct pulse value it will disarm the immobilizer allowing the engine to start.
Transponder car key programming is when you "introduce" the vehicle computer (ECU) to the transponder chip inside the key. This "introduction" may require special machines and tools, or may require a set of actions that can be done by anyone as long as they follow the instructions. The later is called "On Board Programming = OBP"
On Board Programming - programming transponder keys without use of any programming machine or expansive equipment. Some vehicles offer an on board programming option only to add an extra key when you have one or two functioning keys, while other manufactures allow for the transponder system to be programmed on board even for the first master key.
Choose your key type from the list to see its full on-board programming instructions:
⇛ GM Circle-Plus ⊕ / PK3
⇛ Chrysler Dodge Jeep 1998+ Key Programming
⇛ Ford Lincoln Mercury 1996+ Key Programming
⇛ Toyota Lexus 1998+ key programming