Globally Unique Identifier or GUID is a 128-bit integer (16 bytes) identifier used in software applications in order to provide a unique reference number to identify a particular component. It is so unique that there's a very low probability or its impossible that any two or more component has the same value.
Network and Sharing Center
Taskbar and Start Menu
Using GUID Generator: you can use this tool to create your own Guid that can be used for tweaking and customization.
Example: Another Way to Add Icons to Desktop
Generation of random numbers is very important in computer science. It is a computational algorithm designed to generate a sequence of numbers that appear to be random.
This is often use in gambling, cryptography, computer simulation, websites that predicts the users personality especially in social networking websites such as facebook and others.
You can try here: Random Number Generator from your selected range
Using the Random numbers in lottery: http://windowsforus.com/LuckyLotto/
Overall, these systems are related to each other because they can produce unique numbers that can be use in many computer applications.
Being familiar is very important.
Hope this helps!