What qualifies someone as an author
The most widely cited standard comes from the ICMJE, developed for medical journals but applied far more broadly. It sets out four conditions, all of which must be met: substantial contribution to conception or design, or to acquisition, analysis or interpretation; drafting or critically revising the work; approving the final version; and agreeing to be accountable for it.
The last two do real work. Approving the final version means every author has actually read what is being submitted in their name. Accountability means being answerable for the integrity of the whole, not only your own part.
Contributions that do not meet the bar — providing funding, supplying materials, general supervision, routine data collection — are acknowledged rather than credited with authorship. That is not a slight; it is what the acknowledgements section is for.
Under the ICMJE criteria, authorship requires meeting all four conditions — including having read and approved the final manuscript.
Gift, guest and ghost authorship
Gift or honorary authorship means adding someone who did not meet the criteria — commonly a department head or a senior colleague added by convention. It is widespread in some fields and is nonetheless a breach: it dilutes real contributions and assigns accountability to someone who cannot answer for the work.
Ghost authorship is the inverse: someone who did meet the criteria is left off. This is the more serious harm, and it disproportionately affects junior researchers, who are also least able to object.
Both distort the record that hiring committees, funders and immigration adjudicators read. If your name is on a paper you cannot defend, that is a risk to you personally — you have accepted accountability for it.
Preventing and resolving disputes
Agree authorship at the start, in writing, and revisit it when contributions change. An email recording who will be on the paper and in what order, sent when the project begins, prevents most disputes outright. It feels awkward and it is far less awkward than the alternative.
Use a contribution statement. The CRediT taxonomy gives standard roles — conceptualisation, methodology, formal analysis, writing, supervision and others — and many journals now require one. Because it records what each person actually did, it defuses arguments that author order alone cannot settle.
If a dispute arises after submission, journals will generally not adjudicate it. Editors refer authorship disputes to the authors' institutions, and most institutions have a research integrity office with a procedure. Involve them early; a paper can be held indefinitely while an unresolved dispute sits with the editor.