A PSA from an STS Mod: We're family here.

[Zurie]

what is PSA?

[pretzel]

Thank you Remi for that post.
Since you are mentioning non native speakers, a comment from one might be in order: we often have troubles with acronyms.
And this post provides a very good example: the first thing a famous search engine answers when I search PSA is Prostate-Specific Antigen.
A more thorough search produces PSA = Public Service Announcement