Competing interests (also known as conflicts of interests (COIs)) are ubiquitous. One definition is as follows “A conflict of interest (COI) is a situation in which a person or organization is involved in multiple interests, financial interest, or otherwise, one of which could possibly corrupt the motivation of the individual or organization. The presence of a conflict of interest is independent of the occurrence of impropriety.”
Publishers have interpreted competing interests in a number of ways: one example is from the PLOS journals  “A competing interest is anything that interferes with, or could reasonably be perceived as interfering with, the full and objective presentation, peer review, editorial decision-making, or publication of research or non-research articles submitted to a journal. Competing interests can be financial or non-financial, professional, or personal. Competing interests can arise in relationship to an organization or another person.” We welcome other examples.
It is also useful to note that competing interests may arise in the conduct of research itself, and in the context of publishing are thus not restricted to the presentation, peer review, decision making or publication of articles in journals.
These generally understood principles are shared by many journals and publishers. Their interpretation into policy, however, varies (eg, journals ask for a variety of levels of disclosure for financial competing interests).
Refer to the PDF for the full discussion.