Korean Honorifics is a big part of Korean culture and respect, and this is ingrained in the speech as well!
When should you use honorifics (높임말)?
1. When meeting someone for the first time
2. When speaking to people older than you
3. When speaking to your superiors/seniors in the workplace
So when should you drop the honorifics to speak casually?
1. When you become closer to the person after some time
2. When your elder/senior tells you to “Let’s speak casually”.
Here’s a video from Single’s Inferno showing a group of people using polite speech (honorifics) trying to decide whether to speak casually:
Bonus: Try to spot one of the grammar points for honorifics (-요) [-yo] at the end of the sentences.