Where can you park your bike?
You have various options, mostly depending on your local regulation, facilities and length of your parking time:


Bike lockers 
Bike stalls 
Trees, poles or rails (ironically in the picture the bike is locked to a signal pole telling that bikes parked outside the allowed spaces will be removed) 
Bike parking spaces 
Building facade
Car parking space 


The last two are less recommendable, as


your bike won't be linked to something hard to move (a thief can simply load it on a pickup and remove the lock with calm in a quieter place)
it might be unlawful or impeding others (pedestrians, drivers) 
it might not be appreciated (I have seen bikes thrown in the bushes when left in the car space, and 3) understandably really pisses off car drivers)


I am leaving out naive or dumb other parkings  

which are possible but, well, do not praise your smartness (I have seen people locking their bike to a stranger's one)