doc The .doc filename extension is a native file extension used by the closed source document processing application Microsoft Office Word. Initially developed and used by Microsoft since 1983, the filename extension .doc continues to be supported natively even in the most recent iteration of the word processing application Microsoft Office Word 2013. The more recent .docx filename extension however was introduced by Microsoft in Office Word 2007, becoming the default filename extension. Documents to be saved in the .doc format are saved as Word 97, 2003 documents.
bib .bib is a text based file that's created when using LaTeX software. In short, it's a database of references and citations that help to create bibliographies, as well as keeping written citations consistent with each other. .bib files are formatted with BibTeX formatting, and often include information such as author, title, publisher, year, place and edition (although they can include a lot more). A .bib file is often used by authors and academics and is easy to search and navigate, saving the author time and minimising errors. The .bib files can be opened with a number of specific programs on all operating systems, including MikTex for Windows and BibDesk for Mac.