For both research articles and review papers, 3 to 8 keywords should be provided. These keywords should preferably be taken from the controlled vocabulary of subject headings, specifically the standardized nouns or phrases listed in the 'Medical Subject Headings (MeSH) Annotated Alphabetical List'. In cases where no suitable subject heading exists, nouns or phrases that accurately reflect the main themes or concepts of the article can be extracted directly from the title, abstract, hierarchical headings, or other content within the article. These are known as 'free-floating terms' that are not yet included in the controlled vocabulary.