title: Quick sort time complexity
body: <p>I recently read about time complexity and I found out that Quick sort has an average time complexity of <strong>O(nlog(n))</strong>. </p>
  
  <p>Question 1: What I do not understand is how is the <strong>log(n)</strong> present in the time complexity equation?</p>
  
  <p>Question 2: Why do we always use the <strong>big O</strong> notation to find the time complexity of algorithms? Why don't we use other notations?</p>