As Hong Kong preserves Cantonese and the daily communication between Hong Kongers is Cantonese. You will find Cantonese useful in Guangdong region as well. Although the official language is Putonghua (Mandarin), people in Guangdong use Cantonese quite a lot.
This stream if for someone who is:
- Working/Traveling to Hong Kong (or possibly Guangdong)
- A big fan of Hong Kong/ Cantonese Culture