title: What is `weight_decay` meta parameter in Caffe?
body: <p>Looking at an example <a href="https://github.com/BVLC/caffe/blob/tutorial/examples/cifar10/cifar10_full_solver.prototxt#L15" rel="noreferrer"><code>'solver.prototxt'</code></a>, posted on BVLC/caffe git, there is a training meta parameter</p>
  
  <pre><code>weight_decay: 0.04
  </code></pre>
  
  <p>What does this meta parameter mean? And what value should I assign to it?</p>