title: How does Google Web Fonts decide which version of a font to provide to my browser?
body: <p>I have read that "Google Web Fonts tries its best to serve the correct versions, but sometimes there are drastic changes between browsers and operating systems."</p>
  
  <p>I would like to use the following in my CSS: <code>font-family: 'Open Sans', sans-serif;</code></p>
  
  <p>So I included this at the top of my page:</p>
  
  <pre><code>&lt;link rel="stylesheet" href="//fonts.googleapis.com/css?family=Open+Sans:400,700" /&gt;
  </code></pre>
  
  <p>Is this all that I need to do? If that's the case then how can Google Web Fonts decide the correct version for my browser. </p>
  
  <p>Also if I include this then is it likely that the font will exist in my browser. Can I assume that most users will already have a copy of the font?</p>