People seem to be particularly captivated by master keys. I think the device's perplexing nature is what draws people in. How can one key unlock two doors while a different key that opens one door does not open the other? Is the special key the cause of this? Is it the lock's internal mechanisms? I should probably tell you that these answers entail some arithmetic. Before you stop reading (I may have already lost some readers), it isn't anything terribly challenging. Addition and subtraction are at the lowest comprehension level, and exponents are at the highest degree of knowledge (at least as it is expressed here). It's nothing horrible. You should be able to comprehend any master key system, from the most basic to the most sophisticated, after reading this article. One should be able to extrapolate prospective improvements to the system's security if they have a fundamental understanding of it.