title: When a number is written as 0x00... what does the x mean
body: <p>Suppose I was trying to create a mask in C for bitwise operations, like</p>
  
  <pre><code>uint32_t Mask = 0x00000003; 
  </code></pre>
  
  <p>What does the x mean? I see a lot of numbers written with that 0x format and I don't understand why and have been unable to find an explanation that really makes sense to me, maybe I'm not searching the right thing.</p>