Vancouver Citation Style is a style used primarily in biomedical and health settings. It uses numbers as in-text citation that refer back to a corresponding author/work in the reference list. This is to prevent paragraphs from becoming choppy or weighed down by long or repetitive citations in text. Vancouver is extremely similar to NLM Citation Style so they are often referred to synonymously online.
You can manually cite your items in Vancouver Style or you can utilize citation management systems like Zotero (see third tab for next steps) or Endnote to help develop your citation and reference list. You should always double check any citation you pull using database "Cite" functions or citation management tools.
Citing Medicine: The NLM Style Guide for Authors, Editors, and Publishers
"Citing Medicine provides assistance to authors in compiling lists of references for their publications, to editors in revising such lists, to publishers in setting reference standards for their authors and editors, and to librarians and others in formatting bibliographic citations."