title: count vs length vs size in a collection
body: <p>From using a number of programming languages and libraries I have noticed various terms used for the total number of elements in a collection.</p>
  
  <p>The most common seem to be <code>length</code>, <code>count</code>, and <code>size</code>.</p>
  
  <p>eg.</p>
  
  <pre><code>array.length
  vector.size()
  collection.count
  </code></pre>
  
  <p>Is there any preferred term to be used?
  Does it depend on what type of collection it is? ie. mutable/immutable</p>
  
  <p>Is there a preference for it being a property instead of a method?</p>