Side note. Like a P.S.. Usually used on Facebook, Twitter and similar social networking sites.

the definition of SN: means sad note. i just asked my cousin today and she told me. alot of people on facebook, twitter, and other social networking sites use it.

SN- Say Nothing - Don't worry about it, it's no big deal.

The term SNS generally refers to a Social Networking System or the platform that it is served on (Social Networking Software).