title: What are regular expression Balancing Groups?
body: <p>I was just reading a question about how to get data inside double curly braces (<a href="https://stackoverflow.com/questions/17003667/match-text-surrounded-by-and">this question</a>), and then someone brought up balancing groups. I'm still not quite sure what they are and how to use them.</p>
  
  <p>I read through <a href="http://msdn.microsoft.com/en-us/library/bs2twtah.aspx#balancing_group_definition" rel="noreferrer">Balancing Group Definition</a>, but the explanation is hard to follow, and I'm still quite confused on the questions that I mentioned.</p>
  
  <p>Could someone simply explain what balancing groups are and how they are useful?</p>