How do I vertically center text with CSS? [duplicate]

I have a <div> element which contains text and I want to align the contents of this <div> vertically center.

Here is my <div> style:

#box {
  height: 170px;
  width: 270px;
  background: #000;
  font-size: 48px;
  color: #FFF;
  text-align: center;
}

<div id="box">
  Lorem ipsum dolor sit
</div>

What is the best way to achieve this goal?