what does SNS actually do?

[dimm0k]

I have a twitter and FB account and not too long ago I've been getting a notification about logging in where the app info for that notification leads me to SNS. I've always been logged into my twitter and FB account through their respective apps, but this SNS thing looks to be a separate piece that connects the two. Does anyone know what the !@#$ this SNS thing actually does? All searches on this give a vague description on what it is, but nothing on what it actually does. Search results also lead to people removing/disabling it... nice, but still, what does it actually do??