Depending on the person using the nosism different uses can be distinguished:
Royal "we" or pluralis majestatis
The editorial "we" is a similar phenomenon, in which an editorial columnist in a newspaper or a similar commentator in another medium refers to themselves as we when giving their opinion. Here, the writer casts themselves in the role of a spokesperson: either for the media institution that employs them, or more generally on behalf of the party or body of citizens who agree with the commentary.
Author's "we" or pluralis modestiae 
Similar to the editorial "we", pluralis modestiae is the practice common in mathematical and scientific literature of referring to a generic third person by we (instead of the more common one or the informal you):
- By adding four and five, we obtain nine.
- We are thus led also to a definition of "time" in physics. – Albert Einstein
"We" in this sense often refers to "the reader and the author," since the author often assumes that the reader knows and agrees with certain principles or previous theorems for the sake of brevity (or, if not, the reader is prompted to look them up).
This practice is discouraged in the social sciences because it fails to distinguish between sole authorship and co-authorship.