1- Authorea is format agnostic. Overleaf and ShareLaTeX are built around LaTeX. For Authorea, LaTeX is just one of many potential formats. At the moment we offer LaTeX, Markdown, and HTML. We might implement more format in the future too. Being format agnostic is a huge advantage: Authorea is for everybody, and it requires no knowledge of LaTeX or any other markup language. Authorea's HTML editor is a true rich text WYSIWYG editor (What you see is what you get). It makes the experience of writing in Authorea identical to that in Google Docs or Microsoft Word. Users do not need to learn any complex markup. They use Authorea as they would use Google Docs with the additional scholarly features that make Authorea powerful: citation discovery and management, automatic bibliography, mathematical notation, tables, data, and on click one-click  formatting.