As you interact with Facebook you may see terms for ASID and PSID, but what are those used for? Facebook is a really big platform and as we learned earlier this year the majority of the applications you interact with on Facebook are not actually written by Facebook. So there are application developers out there making calculators, quizzes and celebrity look-a-like apps for your enjoyment. But what if one of those application developers is not so honest and forthright in following the rules specified by Facebook for your protection? Well then we have problems like the Cambridge Analytica scandal.
So what is an ASID? To combat this problem Facebook uses a couple different internal identifier’s (ID’s) to track users. They have your main Facebook User ID that is used internally for all of Facebooks purposes, like identifying who uploaded a photo or who was in the photo or who your friends are. But for your safety they don’t allow application developers to access those. So when you connect with an application on the Facebook platform, Facebook creates a new ID for you that is specific to that application. They call this an ASID, or Application Scoped ID.
In addition to that as you connect to different business pages on Facebook, the developers of tools related to the page (ie. Facebook Messenger Bots) also need to be able to reference your identity. For this purpose Facebook creates a PSID, or Page Scoped ID. And each page you connect with will have a different ID to identify you.
The main purpose of this is that if two or more developers of applications for Facebook end up being hacked or store information in a way that is not secure, your ID can not be linked between them. You will have different ID’s available to the developers for each of the applications and pages you connect to.
You can find out more about PSIDs and ASIDs in the Facebook Developer Documentation.