Here is how a traffic stop goes in the US.
Officer calls out stop to dispatcher over the radio.
EX: Dispatch Robert 151 traffic [or stopping] 648 Young - William - Henry (the license plate) at Market and First (location).
Officer contacts the driver, gives his name, department association, advises the driver they are being audio and video recorded, and requests drivers license, vehicle registration, and proof of insurance.
The officer then can do a few things, here is what happens normally:
Officer returns to his patrol car, checks that the date on the registration is valid (not expired), checks that the registration is for the correct vehicle (by license plate). Normally a good dispatcher will send the Department of Licensing vehicle registration information to your in car Mobile Data Terminal. From there you can double check that the license plate is correct and not expired.
At that point the officer will run the drivers license through the dispatcher on the radio. The officer can use the MDT however this is slower and requires the officer to take his eyes off the vehicle. The nice part about running the license over the radio is that 1) you can do it at the car if you are not going to be writing a citation, you never need to return to your vehicle if the paperwork checks out, 2) if the subject comes back with warrants or a suspended license, other officers can hear that and start rolling to your location right away.
If the drivers license checks out clear then the officer can either 1) return to the drivers vehicle and hand back his paperwork and clear from the stop or, 2) scan the drivers license and vehicle registration (the DLicense and registration have barcodes on them, the scanner looks exactly the same as the ones they have at grocery stores, you pull the trigger and the red light flashes out of it) into the computer, put in your location, time of stop, request the service request [sR or case number] from the dispatcher, mark the violation(s) and PRINT the citation out from the computer (no more hand written citations!!!! : D ) then hand this to the driver and clear from the stop.
Hope this gives you an idea of how we do things over here, I know that many departments do things differently (it seems like it changes by each county and definitely by state) but the general process is the same.