When is it appropriate to refer to a person as

[raymondmartin]

when is it appropriate to refer to a person as 애?

[userstk]

It isn’t something easily explained or understood in a few sentences, but here’s the basic situations.

1. children are called 애 by anyone the same age or older.
2. teenagers are called 애 similarly, among themselves and by adults.

One condition, though, is that the person referring to them as 애 should be either the same age or older.
You generally can’t call someone older 애 without sounding inappropriate to the listener.

In a private setting, however, the boundary expands and 애 is used much more broadly than the above.

So 40 something corporate workers might privately refer to their colleagues in another team as 걔들 (those guys), which is an 애-based word.

In the lesson text, they are referring to one of their mutual friends of similar age as 애, which is very common.

애 and its derivatives take up a big part of pronouns and address words in Korean - 얘, 쟤, 걔, 얘들, 남자애, 여쟈애, etc.