title: What does "commercial use" exactly mean?
body: <p>There is a lot of open source engines and software with different licences conditions. Most of them are non-free for commercial use. </p>
  
  <p>The question is what does "commercial use" exactly mean?</p>
  
  <p><em>Example:</em>
  I have site where I propose paid service or software. I want to create blog or wiki section on it. I download appropriated open source projects and deploy on my web site. Is it "commersial use" as I will not earn money on these engines but on the services I propose?</p>