So what determines something being common? Or is that something internal that you don't know the specifics of?
It's based on analysis done by others using leaked passwords on social sites.
The common words database used contains:
- Lists of top 20-100 words used in cracked passwords from various sources
- Top common names according to certain sites
- Dictionary words used by password crackers
Common names are on the list because the analysis showed many cracked passwords contained common names.
The list is English-centric so common international words will probably sneak by.