title_body: How practical is it to learn to develop apps for e-ink Kindles?
upvoted_answer: Learning to develop apps for eBook readers is very practical:
  
  The reason being, the same technology that applies to creating ebooks; also applies to developing websites, software, etc.
  
  Meaning that the skills you learn from developing apps for eBook readers improves your overall skills as a Web or App Developer in general. 
  
  These skills in turn can allow you to start developing more complex skills for becoming a Programmer, Software or Application Developer.
  
  Now that we know the type of jobs related and the career path that follows, we can look at the skills and technology required and used by those in the related industry; to learn how to do the same development.
  
  Basic Skills Required by Web and App Developers:
  
  
  HTML
  CSS
  Javascript
  
  
  An ePub is a zipped up package of content, containing items such as the above, for the purpose of creating the ePub Book/App:
  
  
  HTML (eBook content)
  CSS  (eBook code to stylize layout, etc.)
  JavaScript (For Advanced Use) such as eBook App development.
  
  
  If we learn the above technology then we will have the core skills needed to develop applications for eBook readers.
  
  Learning Priority Order:
  
  
  Learn first: HTML this is the document that holds all your content.
  Learn second: CSS this is the document that stylizes your HTML content.
  Learn third: JavaScript this is the programming language that gives the 'app' like look and ability to your HTML, CSS content. 
  
  
  Where to Learn Online:
  
  
  http://www.lynda.com/ 
  
  courses such as: 
  
  
  "HTML Essential Training"
  "Developing Applications for Amazon Kindle Devices"
  "Creating Ebooks for the Kindle"
  
  Udemy is another website for online learning.
  Code Academy (learn to code)
  Coursera - (Take free online classes from 120+ top universities and educational organizations.)
  
  
  Learning Offline:
  
  
  Books of course! O'Reilly is a good publisher to checkout for technical skills.
  
  
  Comparison Chart of eReader Features and Supporting Platforms:
  
  
  https://en.wikipedia.org/wiki/Comparison_of_e-book_formats#Comparison_tables
  I apologize, there are many more resources and links I'd like to give you but for now my reputation will not allow more than two links so I've provided the most important two links.
  
  
  However, learning to develop apps for the e-ink kindle devices specifically is a bit too narrow for me to personally consider it "practical". 
  
  For example the Kindle Fire has much better support for epub3 formats, app like content, etc.
  
  That being said, what is practical may depend on your use or application as it is a matter of opinion.
  
  What you DO NOT need to know for eBook App Development:
  
  
  Databases such as MySQL, MongoDB, etc.
  Frameworks (although you may find boilerplates that help your app development, packages, libraries, etc.)
  C++, C#, Python, Java to name a few.
  
  
  Good to be Familiar with but may not Need:
  
  
  AJAX/JSON
  PHP
  
  
  Above Skills related to Web Developers more so than having practical use for eBook app development
  
  Final Thoughts:
  
  I've worked for a major Distribution Book Publishing company for the last two and a half years as a digital content engineer managing the QA of our eBooks and can say without doubt, that if you use the above information, it will lead you into the correct direction.
  
  That being said, there are many vendors that provide a service for ebook conversions and ebook app development. At some point you may consider or decide to look into what is available if you have the time or resources.