GUID – None Like U

What is a GUID? The acronym stands for “globally unique identifier”; GUIDs are also called UUIDs, which stands for “universally unique identifier”. (It is unclear to me why we need two nigh-identical names for the same thing, but there you have it.) A GUID is essentially a 128 bit integer, and when written in its human-readable form, is written in hexadecimal in the pattern {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}.
The purpose of a GUID is, as the name implies, to uniquely identify something, so that we can refer to that thing by its identifier and have confidence that everyone can agree upon what thing we are referring to. Think about this problem as it applies to, say, books. It is cumbersome to refer to a book by quoting it in its entirety every time you mention it. Instead, we give every book an identifier in the form of its title. The problem with using a title as an identifier is that there may be many different books with the same title. I have three different books all entitled “The C# Programming Language” on my desk right now; if I want to refer to one of them in particular, I’d typically have to give the edition number. But there is nothing (apart from their good sense) stopping some entirely different publisher from also publishing a book called “The C# Programming Language, fourth edition” that differs from the others.

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