title: What effects do the APP_ENV and APP_DEBUG constants have in a Symfony application?
body: <p>What do the various settings for these environment variables do?</p>
  
  <p>My current guess is that <code>APP_ENV</code> is used only for choosing which config to load (<code>config/packages/{APP_ENV}/*</code>) and <code>APP_DEBUG</code> turns on/off additional console output for kernel events, and enables debugging views for exceptions etc.</p>
  
  <p>Is this correct or do these variables do additional things?</p>