# What is the default bibliography package and backend in LaTeX?

According to this, biblatex and natbib are packages while biber and bibtex are backends. If I don't specify either any package or any backend, it still compiles fine. Which package and backend combination is being used in this case?

demo.tex

\documentclass{article}
\begin{document}

\nocite{*}
\bibliographystyle{ieeetr}
\bibliography{pub}

\end{document}


pub.bib

@article{janssen1996evaluation,
title={Evaluation of the DNA fingerprinting method AFLP as a new tool in bacterial taxonomy},
author={Janssen, Paul and Coopman, Renata and Huys, Geert and Swings, Jean and Bleeker, Marjo and Vos, Pieter and Zabeau, Marc and Kersters, Karel},
journal={Microbiology},
volume={142},
number={7},
pages={1881--1893},
year={1996},
publisher={Soc General Microbiol}
}

@article{vos1995aflp,
title={AFLP: a new technique for DNA fingerprinting},
author={Vos, Pieter and Hogers, Rene and Bleeker, Marjo and Reijans, Martin and Van de Lee, Theo and Hornes, Miranda and Friters, Adrie and Pot, Jerina and Paleman, Johan and Kuiper, Martin and others},
journal={Nucleic acids research},
volume={23},
number={21},
pages={4407--4414},
year={1995},
publisher={Oxford Univ Press}
}

• There is no backend predefined, as LaTeX by itself does not launch any backend. But many editors are configured to launch a backend. Also, biber requires biblatex to work (albeut biblatexcan use bibtex as a backend). Typically, the code you posted will work with bibtex. – Bernard Apr 1 '17 at 18:21

There is not really any sense in which there is a 'default' bibliography package for LaTeX. In order to compile your sample document you have used both a TeX engine (most likely pdflatex) and bibtex, since the IEEEtr.bst file that is used when you add \bibliography{IEEEtr} requires bibtex.
This only appears to be a 'default' because your editor is probably set up so that bibtex is the default program for bibliographies.
Had your editor been set to use biber as the default program, your document would have failed.
As you can see from your sample document, a specific bibliography package (such as natbib) is not strictly needed when using bibtex as the backend. However natbib+bibtex provides good support for Author/Year type citations, which is why many people use it. (biblatex+biber also provides good Author/Year support along with many other citation styles.) As discussed in the question you link to, natbib and biblatex are of course incompatible with each other.
• Yes, thank you. It seems quite common for people to try using natbib and biblatex, so I think redundancy is safest ;). – cfr Apr 2 '17 at 15:53
• I implicitly assumed that to use bibtex backend, I must use either natbib or biblatex package. This follows from the fact that I don't understand what functionality a backend provides vs. what functionality a package provides very clearly. – Holmes.Sherlock Apr 2 '17 at 18:54
• @Holmes.Sherlock You must use bibtex with natbib. You should ideally use biber with biblatex and not bibtex. The two programs are not really comparable: bibtex does both sorting and formatting, while biber is really only responsible for sorting (and very sophisticated sorting in fact); biblatex does all the formatting. – Alan Munn Apr 2 '17 at 19:16