GUID stands for Globally Unique Identifier.

GUID is the Microsoft implementation of the **Distributed Computing Environment** (DCE) **Universally Unique Identifier**(UUID).

A GUID is a 128-bit value consisting of one group of 8 hexadecimal digits, followed by three groups of 4 hexadecimal digits each, followed by one group of 12 hexadecimal digits.

The following example GUID shows the groupings of hexadecimal digits in a GUID:

**6A35C390–D0E4–403F–85C2–3593D7218AE9**

According to Microsoft’s article GUID Structure** :**

There are four parts of GUID

** **

** Part 1: **Specifies the first 8 hexadecimal digits of the GUID.

** ****Part 2: **Specifies the first group of 4 hexadecimal digits.** **

** Part 3: **Specifies the second group of 4 hexadecimal digits.** **

** Part 4: **Array of 8 bytes. The first 2 bytes contain the third group

of 4 hexadecimal digits. The remaining 6 bytes contain the

final 12 hexadecimal digits.

There are 2 ^ 128 possible GUIDs which is equivalent to approximately **40** Billion Billion Billion for every person on earth.