natbib package is designed especially to provide author-year type citations as used in the natural and social sciences. It has been in use for many years, and as a result has a large user base and a large number of pre-made bibliography styles created that match the requirements of many scientific journals.
You should use this tag for questions about the
natbib package itself or for any associated
.bst files (bibliography styles). You might also want to use the more general bibliographies tag in addition to this tag if your question concerns formatting bibliographies generally.
biblatex has begun to gain popularity. If you are just beginning to use bibliographies, use non-Roman scripts, or need bibliography styles predominant in the humanities, you should probably be using
biblatex. See the biblatex tag info for more information.