title: What is a build tool?
body: <p>For past 4 years, I have been programming with Eclipse (for Java), and Visual Studio Express (for C#). The IDEs mentioned always seemed to provide every facility a programmer might ask for (related to programming, of course). </p>
  
  <p>Lately I have been hearing about something called "build tools". I heard they're used almost in all kind of real world development. What are they exactly? What problems are they designed to solve?  How come I never needed them in past four years? Are they kind of command-line stripped down IDEs? </p>