A converter from TeX and LaTeX to SGML-based formats such as (X)HTML, MathML, OpenDocument, and Docbook, providing a configurable (La)TeX-based authoring system for hypertext. TeX4ht does not independently parse (La)TeX source (so it avoids the difficulties encountered by many other converters, arising from the irregularity of (La)TeX syntax). Instead, TeX4ht uses (La)TeX itself (with myriad macro modifications) to produce a helper DVI file that it can then process. This technique allows TeX4ht to approach the robustness characteristic of restricted-syntax systems such as gellmu. Full releases of TeX4ht are no longer made, both because it is technically difficult to do so and because their utility is questionable. Nevertheless, TeX4ht is actively maintained. So, current source files are held on CTAN, and updated from the development repository frequently. Creating the myriad derived files from them is nontrivial, and generally done with the Makefile in development, from which the TeX4ht package in TeX Live is updated.