title_body: Should a person learn DocBook in 2019?
upvoted_answer: I use docbook for my ebook workflow, so I have a good deal of insight into this question. 
  
  Employment-wise, I haven't seen a lot of demand for docbook, though occasionally it is called for in open-source documentation. A lot of programmers know about it, and tech pubs know about it. I'm guessing that DITA is somewhat more popular in tech writing circles.  Knowing how to do XSLT is a somewhat hard to find skill (even among programmers). 
  
  Some positives: 
  
  
  The docbook-apps mailing list is small but dedicated. I usually get a
  good answer fairly soon. 
  Docbook -- like DITA -- is a modular XML-based method for producing
  documentation. I've repurposed it for ebook publishing. The semantics
  are rich, and indeed, a branch called DOCBOOK FOR PUBLISHERS, uses
  the same tools, tosses out some of elements used only for technical
  pubs and adds a few ones for poetry and drama. 
  The best thing about it is that it's easy to read, it's easy to use
  for version control and you can use general XSLT in a customization
  layer to add functionality you need. 
  the HTML output is very clean, so it's easy to customize the CSS. 
  XML Oxygen is an extremely good client-side tool for producing and
  transforming docbook files.
  The standard is likely to remain stable and backward compatible for a long while. For now at least Oxygen is adequate as a tool. 
  
  
  Among the negatives:
  
  
  Even though it's theoretically possible to produce epubs from docbook
  xml and it's possible to use a framework like ANT to produce the
  final output, I find it unwieldy. Instead I use the built in XSLT
  transformations in Oxygen XML, and actually I do some manual steps --
  moving image files into a directory, zipping the files up.
  I often perform these manual steps because I'm too lazy/stupid to
  write appropriate xslt code, but sometimes the stupid solution is the
  easiest. 
  Because Docbook outputs into several files, often you will see some
  extra elements and attributes which are remnants of this
  functionality. Example: &lt;div class="titlepage"&gt; 
  I have not seen any server-solutions for Docbook output although I'm
  sure they exist.
  
  
  The future: 
  
  3 trends I see that may suggest declining importance of docbook. 
  
  First, a lot of source is being written in markdown. I am seeing more tools (like Pandoc) to allow for richer presentation. Markdown isn't xml and not really a semantic language. 
  
  Client-based WYSIWG ebook tools are improving. None are really great (maybe Calibre?), but every year means more functionality and ease of use. 
  
  Static Site Generators - if they become more widespread, might result in more web-based ebooks. Docbook has a website builder function which I have never used btw. Hope this helps.