When we use "on delete cascade" constraint in mysql?

Imean it could be either both i get why it could be part of being human because some people just look at the famous people and they probably think to themselves that if that person does that well then i should do it and maybe i’ll get the attention and followers that i want. it could be also connected to the current young phenomenon because some kids at the age of 14 are already famous like for doing the most nasty things probably without even thinking who would probably watch such thing, they just do it cause they know they’ll get the attention that they want. sorry if i didn’t use correct grammar.but hope this answers the question< 3