What does UUID format 8-4-4-4-12 format indicates?

[Sara]

It is an unique identification code but what does the format 8-4-4-4-12 signifies? Why this format is used?

[Mahesh Venkitachalam]

This answers your question on the byte grouping in uuids:

programmers.stackexchange.com/.../why-are-uuid-guids-in-the-format-they-are

(To summarise, it comes from the "time and MAC address" form of UUID.)

The full specification for UUID (PDF) can be found here:

www.itu.int/.../en