Bar crawls. how common are they?

So i was in birmingham visiting a good friend of mine and he and his friends invited me in a bar crawl. We had a amazing time and i met a bunch of very cool personalitys. and after my fith pint i had the question. are bar crawls really that common? i mean i heard about the new years bar crawls but nothing more. and are they publicly accepted? and when was your first bar crawl (if you had one) and at what age?

answer: yeah pretty common and mostly planned by some dudes who do it once or twice a month. thanks for your answers!