# What bibliography is used if no package is loaded? [duplicate]

I used to think that to use a bibliography, one always needs to load either `biblatex` or `natbib` however in my current thesis template, neither package is loaded and yet there is a bibliography (from `.bib` file generated by JabRef in `biblatex` mode).

When I try to use the `biblatex` package, I get errors reffering to the way the bibliography style is set.

What is the Latex default bibliography "tool"? Also if everything's working fine, why would I want to use `biblatex`?

(Using TexStudio, TexLive, JabRef)

• There a "default" without bibtex nor biblatex nor .bib files. And there are several BibTeX bibliographic styles without any package (plain, abbrv, etc.) but using bibtex and .bib files. Some packages allow additional bibtex styles, an biblatex is an alternative system even more powerful to use the .bib files. Maybe this answer can you clarify something about. – Fran Sep 17 '18 at 18:04
• Note also that using a "template" perhaps natbib or another package is already loaded with some custom class. That is, even if there are nothing in the preamble, the `\documentclass{whatever}` load `whatever.cls` which in turn could load also some package . – Fran Sep 17 '18 at 18:36
• Yep, i checked that even with \listfiles, but nothing was loaded. the documentclass is scrbook. – Xaser Sep 17 '18 at 19:21

The default LaTeX tool for creating bibliographies -- i.e., the LaTeX method that requires no external programs at all (not bibtex, not biber, etc) and no additional packages (not `natbib`, not `biblatex`, etc) -- is the `thebibliography` environment, populated by `\bibitem` items -- one `\bibitem` per entry. The `thebibliography` environment is pretty much free-format, and it's up to the user to determine all aspects of every single entry. In fact, each and every single entry has to be entered by hand.
• What is `abd`? You said each abd.... – Sigur Sep 17 '18 at 21:06