With approximately one billion people using Microsoft Office, the DOCX format is the most popular standard for exchanging document files between offices. Its closest competitor – the ODT format – is only supported by Open/LibreOffice and some open source products, making it far from standard. The PDF format is not a competitor because PDFs can’t be edited and they don’t contain a full document structure, so they can only take limited local changes like watermarks, signatures, and the like. This is why most business documents are created in the DOCX format; there’s no good alternative to replace it.

While DOCX is a complex format, you may want to parse it manually for simpler tasks such as indexing, converting to TXT and making other small modifications. I’d like to give you enough information on DOCX internals so you don’t have to reference the ECMA specifications, a massive 5,000 page manual.