What exactly is GUID? Why and where I should use it?

Question

What exactly is GUID? Why and where I should use it?
I\'ve seen references to GUID in a lot of places, and in wikipedia, but it is not very clear telling you where to

Answer 1

For me it's easier to think of them as simply "128-bit random values". Which is essentially what they are. There are some algorithms for including a bit of information in a few digits of your GUID (thus the random part gets a bit smaller), but still they are pretty large almost-random values.

Since they are so large, it is extremely unlikely that two GUIDs will ever be generated that are the same. For all practical purposes, every GUID ever generated is unique in the world.

I'll leave it to you to figure out where to use them, but other answers already have some examples. Let your imagination run wild. :)