Nintendo Network IDs are yours & other's unique identification on Miiverse.
The purpose of NNIDs are to be able to tell the real user from possible fake users, make easy user searches, & to be able to track users easier etc.
Possible Bans Related to NNIDs
- Giving other users the password to your NNID
- Having an inappropriate NNID
- Telling users your age (sometimes)
- All Miiverse Admins have the same NNID being miiverse_admin. This is probably done so that the Admins can remain discrete & for security reasons.
- The biggest giveaway to an impersonator is most likely the NNID as you cannot have the exact same NNID unlike most other things (ex. Birthday.) Otherwise, it is likely a mess up on the impersonated user's Mii for the impersonator (usually with more complex Miis.)
- If you want to avoid being impersonated via your NNID then the best thing is to not have any lowercase ls or any capitalized Is since they look very similar & other letters are more unique when it comes to how they look.
- Remembering a user's NNID is really useful incase they get banned as then you have way more accurate searches over searching multiple people with the same name (usually excluding people with special characters.) This becomes not as useful after 6/24/15 however as then all users get banned over one user's violations.
- If you or Nintendo delete an NNID for whatever reason then all data will be lost. You will also even lose the money that you have on that account's E-shop accounts.
- You cannot make an NNID on the Web Version.