LaTeX (pronounced Lah-Tech or Lay-Tech) is a document preparation language used for typesetting technical documents. It is widely used by scientists, engineers and other technical writers because it makes it easy to typeset mathematical equations, formulae, data and images.
Documents are written with LaTeX by creating a plain text file with the .tex extension, and using codes to indicate markup which determine layout and appearance in the finished document. The file is run through a processor to produce the typeset document. Editing tools allow you to write and render the LaTeX content of a document ready for publication.
BibTeX is the reference management tool for LaTeX. You can export reference libraries from Zotero, Endnote and Mendeley into BibTeX. BibTeX files have the file extension .bib.
There are a number of editing tools available which simplify using LaTeX and allow rendering directly in the editor.
Online LaTeX editing tools can support collaborative writing, although free versions may be limited.
Authorea supports collaborative authoring with LaTex. Limited free version, or subscription.
Overleaf is an online subscription LaTex writing tool. Sign up as a single user or collaborate with colleagues. Subscription based.