title: Difference between -net user and -net nic in qemu
body: <p>I am trying to boot a virtual machine with my a custom IP address using <code>qemu-system-x86_64</code>. Referring to <a href="http://qemu.weilnetz.de/qemu-doc.html" rel="noreferrer"><code>qemu-system-x86_64</code>'s tutorials</a>, I found this:</p>
  
  <blockquote>
    <p>-net nic[,vlan=n][,macaddr=mac][,model=type] [,name=name][,addr=addr][,vectors=v]
            Create a new Network Interface Card and connect it to VLAN n (n = 0 is the 
    default). The NIC is an e1000 by default on the PC target.
       -netdev user,id=id[,option][,option][,...]</p>
  </blockquote>
  
  <pre><code>-net user[,option][,option][,...]
      Use the user mode network stack which requires no administrator privilege to run. 
  </code></pre>
  
  <p>I am not able to understand the difference between these two options.</p>
  
  <ul>
  <li>What is a user mode network stack?</li>
  <li>And why do I need it?</li>
  <li>What is the difference between the <code>nic</code> and <code>user</code> parameters?</li>
  </ul>