I've always been taught that the word 'staff' (as in employees of a company) is plural, so there is no such word as 'staffs'.
Just today, however, while editing a draft article, I came across the word 'staffs' being used in a sentence:
Congratulations to the following staff who have passed all 3 modules of the certification course successfully:
Making a research on the web to confirm the invalidity of the word 'staffs' I discover two contradicting versions of advice from two different English Expert sites.
1) English plural - Wikipedia, the free encyclopedia
Note 2: For staff in the sense of "a body of employees", the plural is always staffs; otherwise, both staffs and staves are acceptable, except in compounds; such as flagstaffs. The stave of a barrel or cask is a back-formation from staves, which is its plural. (See the Plural to singular by back-formation section below.)
2) General Writing and Grammar Help: Is "staff" plural/subject verb agreement
Collective nouns are always tough, and it usually depends on how you intend to use the word "staff." If you mean the staff AS A UNIT, then use the singular verb form (provides). If you mean every member of the staff, use "provide."
Please advise which is correct?
The other issue is whether the verb should agree with singular "staff" gramatically ("Our staff is always ready to help you") or notionally ("Our staff are always..."). American usage generally favors the former whereas British often favours the latter.