Vancouver style follows the rules established by the International Committee of Medical Journal Editors. These rules are known as the Uniform Requirements for Manuscripts Submitted to Biomedical journals.
Vancouver is a numbered style, where a number is allocated to a source in the order in which it is cited in the text (if it is cited again, the same number is used).
The Vancouver style is commonly used in medical and scientific journals (e.g. by the National Library of Medicine and the American Medical Association) and for the health sciences, with slight style variations between journals (e.g. use of superscript).