Supplementary material
Also called: supplemental material, supporting information
Files published alongside an article — data, code, extended methods, extra figures — hosted with it but outside the main text.
Supplements carry what will not fit: full protocols, raw tables, videos, analysis scripts. In many fields the methods that actually let you reproduce a study live there rather than in the paper.
Cite it as part of the article, identifying the specific item (“Table S3 in Rivera & Chen, 2021”). Where the data or code has its own DOI in a repository, cite that separately — it is a distinct, citable output.