Ask HN: How to avoid being arrogant?

I have been thinking about arrogance for the last five years and I still cannot grasp it.

Answering any of the questions below will help to discuss the premier question:

1 - What exactly is arrogance?

2 - How do you detect arrogance?

3 - Why some people become arrogant?

4 - Is it always bad? If so, how do you avoid being arrogant?