Where can you park your bike? I've started biking and see its potential for being able to go around the local area. But when you are running errands (biking to a store or the bank or something) you have to physically put it somewhere while you shop. The one time I ever did this was to pick a pizza. I put it in the place of a car, grabbed the pizza inside, and left. (I put a light lock on it) I don't know if this is proper or even legal. This is a very stupid question, but I can't find the proper phrasing for an answer.
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)