This section specifies the exact contributions of each author in a narrative form. It is not a required section but is included in the final publication if provided. The section should be within the manuscript, between the (optional) Acknowledgements and the (mandatory) "Conflicts of Interest" section.
Sentences like "All authors contributed equally to this manuscript." do NOT belong here, but rather using an equal contribution footnote in the metadata (see Can there be two corresponding authors?).
Members of a collaborative (group) author should be listed and acknowledged here.
Authors should be referred to by their initials, and contributions should be specified (eg, "developed and tested the search strategy", "contributed to study design, methodology, data analysis, and manuscript preparation").
Example: JM wrote the manuscript and provided data for Table 1. SGH conducted the patient interviews.