Which aircraft did I photograph at ZRH?
One of the simplest things you can do is to type in the registration into Google which will normally give you results of the type and history of the aircraft.

Otherwise, many airlines don't operate too many types of aircraft so a quick look on Wikipedia and looking through 'fleet' should show you which types it may be, from which elimination should be pretty quick.

The registration is normally visible on the back of the fuselage and under the wing (D-ABEP on the rear fuselage below), and the last two letters are (often) printed on the aircraft 'forehead' above the cockpit windows, the top of the tail and the nose gear doors (EP on the nose gear doors below).





Aircraft from your photos: 


Boeing 737
Airbus A320
RJ85
Airbus A320
Airbus A321
Fokker 100