title: Understand SonarQube and its testing coverage
body: <p>i am a Beginner with SonarQube and really tried to google and read a lot of community pages to understand which functions SonarQube offers.</p>
  
  <p>What i dont get is: What does the test coverage in SonarQube refer to? 
  If it says for example that the coverage on New Code is 30% what does new code mean?</p>
  
  <p>And when does SonarQube say that a issue is a bug? Is the analyzed code compared to a certain standard in order for SonarQube to say that there is a bug?</p>
  
  <p>I hope someone with more knowledge about SonarQube can help me understand it. Thank you very much</p>