Did you ever think why your door key opens only your lock, and each of your neighbors' keys opens only each of theirs -- but the superintendent can open everyone's locks? How many keys does he carry anyway? The key to this question is in this quiz.
How much do you know about how car engines work? And how much do you know about how the English language works? And what about how guns work? How much do you know? Lucky for you, HowStuffWorks is about more than providing great answers about how the world works. We are also here to bring joy to your day with fun quizzes, compelling photography and fascinating listicles. Some of our content is about how stuff works. Some is about how much you know about how stuff works. And some is just for fun! Because, well, did you know that having fun is an important part of how your brain works? Well, it is! So keep reading!