< and & are only used to start tags and entities

• Good:

  
  <H1>O'Reilly &amp; Associates</H1>
  

• Bad:

  
  <H1>O'Reilly & Associates</H1>
  

• Good:

  <CODE>for (int i = 0; i &lt;= args.length; i++ ) { </CODE>
  

• Bad:

  <CODE>for (int i = 0; i <= args.length; i++ ) { </CODE>