Lets talk about commonly used automotive terms.
AFR- Air/Fuel Ratio. This is the Amount of Air molecules divided by the amount of fuel molecules.
AIT- Air Intake Temperature Sensor Also called an IAT sensor
CTS- Coolant Temperature Sensor
CMP- Camshaft Position Sensor
CKP- Crankshaft Position Sensor
Lambda- Lambda is the preferred method of measuring air/fuel ratio as it is more universal. Lambda of 1.0:1 is stoic for any fuel type, and it just scales accordingly. Gasoline Stoic is 14.7, while methanol is approx 6.5:1 ratio for that "perfect burn". Most vehicles make target peak torque around .85 lambda (ones that don't require fuel for thermal management, turbocharged vehicles like it around .72-.78 on gasoline). Lambda is easy to fine, take your actual AFR and divide it by your Stoic AFR, that's your lambda!
LTFT- Long Term Fuel Trims
ICS- Idle Control Solenoid. Steppers or pulse style usually. Our cars uses a steppers style solenoid for idle control.
MAS- Mass Airflow Sensor
MAP- Manifold Absolute Pressure Sensor
O2- Oxygen Sensor, available in narrowband and wideband.
STFT- Short Term Fuel Trims
TPS- Throttle Position Sensor, on our vehicles there is a single 0-5v signal. 0 being closed, 5v being wot. 4.8v and + is acceptable
Closed loop- Preset fuel control, usually on a percentage of available adjustment. Pretty much this is idle and part throttle/driving conditions where engine stability is predicted and doesn't change rapidly. Most OEM's have around 15% available for fuel trimming. This is where narrowband oxygen sensors prevail and are important to use.
Open loop- Commanded air/fuel ratio based on a VE chart of the engine. All WOT fueling is done in "open loop". The ecu isn't checking and double checking airflow readings/rpm/vacuum and is just going to your VE table, grabbing a cell, and plugging that much fuel into the engine.
Narrowband Oxygen Sensor- These are factory 02 sensors and found in virtually all modern production vehicles.
Wikipedia actually has a good write-up on oxygen sensors:
http://en.wikipedia.org/wiki/Oxygen_sensor
They emit a 0-1v signal. They are highly accurate around stoichiometric air/fuel ratio and help keep a car at that afr. They achieve this accuracy via "switching" see below.
Above is a great illustration from a great wideband manufacture, PLX Devices.
As you can see from above, there is a narrow range of voltage that is emitted from the oxygen sensor that lets the ecu know which side of stoic the vehicle is running (Most oems consider stoic 14.5-15.3afr) How narrowband/closed loop o2 feedback works is the ecu will poke or "trim" positive or negative (according to what the original reading was) and try to keep the vehicle on that exact switching point...this is called your STFT (short term fuel trim). Most OEM's shoot for a 3% accuracy and window. They will "trim" lower than that, but they won't be saved into LTFT's most likely.
LTFT's are stored trims the ecu has "learned". This is how oem cars can seem to run fine with larger injectors at idle/cruise, the ecu is constantly learning/adapting. The OEM's built this in to deal with declining/failing injectors, engines, sensors, and climate changes. Very important for OEM's to have for emissions controls as well. As vehicles age, systems weaken and they need to run similar to how they ran when they were new, for both performance and emissions compliance.
Wideband Oxygen Sensors- These are sensors that are based on a 0-5v scale and most commonly spit out a liniar signal. 0v being rich 5v being lean. They usually read/measure from around 9 afr to 22 afr. This is mostly based in the controller and how it is configured.
The beauty of these is how spread out the signal is. With 5volts to use, a .100 change in voltage makes a change in actual afr ratio on the "point" scale (14.7:1 vs 14.5:1, etc..).