What's the use of China PICC invitation code?

It is equivalent to entering the registration code when you use a software. It's the same as an invitation in real life. Only when you receive the invitation code can you register your account.

China PICC invitation code can be filled in or not, which will not affect the normal use. App invitation code is mainly used to distinguish which user or promotion channel (invitation code) the invited user was invited from, so as to reward users or share channels (CPS, CPA).