What does " Part X" means?

Game Discussion General Discussion
1

This question has puzzled me for a long time. What rules are used to convert the first, second, and third parts in the title?

For example:
Next Major Update - Rumor Round-Up & Discussion (Part 1/2/3)

2

After 10k messages the Thread gets closed and an new one opens with Part 1, again 10k… Part 2 and so on…