This word comes up in [[AWS Identity and Access Management|AWS IAM]] and [[Windows Active Directory]] ([[User Principal Name]]) and it annoyed me because I could not understand what the word was trying to convey. In [[Windows Active Directory|AD]], [[User Principal Name|UPN]] must be the main name of a user. But why? Can a user have secondary names? This is what bugged me. See [User Naming Attributes](https://docs.microsoft.com/en-us/windows/win32/ad/naming-properties). > A UPN is an Internet-style login name for a user based on the Internet standard [[Request for Comments|RFC]] 822. The UPN is shorter than a distinguished name and easier to remember. By convention, this should map to the user's email name. The point of the UPN is to consolidate the email and logon namespaces so that the user only needs to remember a single name. In [[AWS Identity and Access Management|AWS IAM]], it just means the entity (person or application) that makes the request. I would not choose the word principal to describe this. ## Definition First in order of importance; main. ## Context In The Simpsons, Principal Skinner is the principal of the school. The boss, or rather the most important person at the school. ## Connections ? ## Morphology and etymology From primus "first". Prince. Principal. Prime. Primary. Primus. Priority. [[Reasoning from first principles]], which is kind of saying that [Why are prime numbers called prime?](https://primes.utm.edu/notes/faq/WhyCalledPrimes.html): > In a multiplicative sense prime numbers are thus the first numbers, the numbers from which the other numbers all arise (through multiplication).  All other numbers (positive integers) are measured by primes, but primes alone are measured only by units.  This makes primes first. A prime number is divisible only by 1 and itself. Having exactly two integral factors: itself and unity (1 in the case of integers).