MARK
Run 
<!DOCTYPE html>
<html>
   <body>
      <h1>The mark tag example</h1>
      <p>Do not forget to buy <mark>milk </mark> today.</p>
      <p>Do not forgot to <marK>study </marK> today</p>
      <p>Do not go Outside cause its <mark> quarantine</mark></p>
   </body>
</html>