Vancouver is a numbered referencing style commonly used in medicine and science, and consists of:
citations to someone else's work in the text, indicated by the use of a number
a sequentially numbered reference list at the end of the document providing full details of the corresponding in-text reference
It follows rules established by the International committee of Medical Journal Editors, now maintained by the U.S. National Library of Medicine. It is also known as Uniform Requirements for Manuscripts submitted to Biomedical Journals.
Vancouver system, also called citation-sequence system (C-S system) or the author-number system, is a broad term for a style of citation and referencing, wherein, each citation in the text is given a number according to the order in which it first appears in the text, and the end references are listed in the sequence in which they first appear within the text. Vancouver is a preferred system for health and medical sciences,
The citation in the text is indicated by an Arabic numeral, often set as superscript as1 or a number in parenthesis as (1), square bracket [1], or superscript1. After finalising citations in the text, the reference sources would be listed at the end of the document in the order of their position in the text. If you want to cite an already cited source with a number again in the document, you need to refer to it by its original number. The year of publication is often given after the publisher's name in the case of books or after the journal’s name for articles.
Vancouver system is a reader friendly referencing system because one can quickly go through the details of references cited in the order of their appearance in the text.
Two more variants of Vancouver system are prevalent where references are identified by numerals, the citation-name system and the footnote method.
The Council of Science Editors (CSE) recommends the Citation-Sequence (Vancouver) system in addition to the Name-Year (N-Y) system and the Citation-Name(C-N) system for science disciplines.