BibTeX
Also called: .bib
The reference format used with LaTeX, storing each source as a typed record of field–value pairs in a .bib file.
A BibTeX entry opens with an entry type and a citation key — @article{rivera2021mapping, ...} — followed by fields such as author, title, journal, year. The key is what you cite with in LaTeX (\cite{rivera2021mapping}), and the formatting is applied later by a bibliography style file.
BibTeX is the lingua franca of citation interchange far beyond LaTeX: nearly every reference manager, publisher, and repository can export it, and Google Scholar offers it on every result. That makes it the most portable way to move a bibliography between tools.
Its quirks are worth knowing. Braces protect capitalisation ({DNA} stays capitalised), the entry type constrains which fields are required, and duplicate keys silently break a document.