DVI is the most compact format which retains the full typographic complexity of TeX and LaTeX documents. The computer client which visualizes DVI files must have access to appropriate fonts, since these fonts are not embedded in the DVI file. capabilities by being self-aware of the document format metadata.
I produce DVI files with LaTeX and BibTeX. View DVI files with the freely available program xdvi.
HTML is the lingua france of the Web. It retains very little typographic or compositional information.
I produce HTML files with htlatex, latex2html, or tth -Lfoo -p${TEXINPUTS}). View HTML files with any browser.
LaTeX source files work with the TeX typography engine. I write all my documents in LaTeX, so the source files contain all the typographic and compositional information.
I use LaTeX and BibTeX to produce DVI files. I produce LaTeX files with emacs and AucTeX. View LaTeX files with any editor.
PDF is a stripped down version of Postscript which saves space by using binary data representation and adds capabilities by being self-aware of the document format metadata. Thus, PDF files are a compact way of storing letter quality documents.
I produce PDF files with pdflatex and thumbpdf. View PDF files with the freely available programs Acrobat reader and/or xpdf.
Text files contain pure ASCII text with no formatting commands.
I produce TXT files with pdftotext. View .txt files with any editor.