title: What's the difference between a runtime environment, a runtime engine, and a runtime library?
body: <p>I'd like to make sure I have the definitions of a few terms associated with runtime correct. </p>
  
  <p>Does the following make sense?</p>
  
  <p>A <strong>runtime system</strong> (aka runtime engine) is software that is designed to aid the execution of a computer program while it is running. The runtime system acts as the gateway for the <strong>runtime environment</strong>, which is an abstraction of the underlying system a program is running on.</p>
  
  <p>Is this correct?</p>
  
  <p>Also: 
  How is do you distinguish between a runtime system and a runtime library?
  What exactly does "runtime" by itself refer to? E.g. "node.js is a Javascript runtime"</p>
  
  <p>Thanks!</p>