title: IntelliJ IDEA: What qualifies as an SDK?
body: <h1>What exactly is an SDK, in the context of IntelliJ?</h1>
  <p><img src="https://i.imgur.com/61GskZ2.jpg" alt="Add New SDK dropdown menu in IntelliJ IDEA Project" /></p>
  <p>For the education of non-Java developers of PHP, Ruby or JavaScript applications who prefer IntelliJ IDEA for its Polyglot capabilities, do any knowledgeable IntelliJ IDEA users please have a moment to explain:</p>
  <h1>2. Why is the concept of an SDK (in the context of InteliJ) essential only to Java?</h1>
  <p>As <a href="/users/3006544/ryan-j">Ryan J</a> writes in his answer below:</p>
  <blockquote>
  <p>An SDK (such as Java) can be very big, containing a lot of information and capability. Other SDK's may simply be a set of API's or libraries, and as such, may not be as conducive to being used with an IDE, and could be deemed as &quot;convenient&quot; from the perspective of a user that is not familiar with the concept of an SDK in the &quot;Java&quot; sense.</p>
  </blockquote>
  <p><em>Update: 1 Year Later.</em> I've edited this question to focus on the simplest most useful answer I've found, and am awarding the correct answer to Ryan J. <strong>Simply put: Java is a platform. Platforms have SDKs.</strong> PHP, JavaScript, and Ruby are languages, with various available runtime environments not mentioned in this Q&amp;A. This programmer now uses Sublime Text 3 for developing in those languages. At the expense of much processor overhead there were neat features in IntelliJ for refactoring, etc.. but IMO they are no match for having tight regex game.</p>
  <h2>2. What is the &quot;Ruby SDK&quot; option if not an SDK?</h2>
  <p>JetBrains support writes:</p>
  <blockquote>
  <p>Ruby has SDK for convenience as users may need multiple Ruby/RVM versions. The same applies to Python, multiple different virtualenvs can be defined and a user may need to switch between them (including Remote SDK on the server via SSH).</p>
  </blockquote>
  <h1>3. What is the &quot;PHP Interpreter&quot; option if not an SDK?</h1>
  <p>JetBrains support writes:</p>
  <blockquote>
  <p><strong>PHP has no SDK in IDEA/PhpStorm.</strong></p>
  <p>See <a href="http://youtrack.jetbrains.com/issue/WI-22627#comment=27-720859" rel="nofollow noreferrer">http://youtrack.jetbrains.com/issue/WI-22627#comment=27-720859</a></p>
  <p>PhpStorm Project Lead <a href="/users/107788/alexey-gopachenko">Alexey Gopachenko</a> is against the PHP SDK configuration. It would be probably removed or will be available only in IDEA, not sure.</p>
  </blockquote>
  <p>In my opinion, this makes a lot of sense. PHP is a language. We can use IDE extensions to better understand that language, but its API is completely exposed by text scripts.</p>
  <p>Shameless big up my personal favorite PHP workflow, <a href="http://phundament.com/" rel="nofollow noreferrer">Phundament</a>. This programmer no longer endorses PHP.</p>