::after

a::after {
  content: " (" attr(href) ")";
}

.dead-link {
  text-decoration: line-through;
}

.dead-link::after {
  content: url("/shared-assets/images/examples/warning.svg");
  display: inline-block;
  width: 12px;
  height: 12px;
}

<p>
  The sailfish is named for its sail-like dorsal fin and is widely considered
  the fastest fish in the ocean.
  <a href="https://en.wikipedia.org/wiki/Sailfish"
    >You can read more about it here</a
  >.
</p>

<p>
  The red lionfish is a predatory scorpionfish that lives on coral reefs of the
  Indo-Pacific Ocean and more recently in the western Atlantic.
  <a href="" class="dead-link">You can read more about it here</a>.
</p>

::after {
  content: /* value */;
  /* properties */
}

<p class="boring-text">Here is some plain old boring text.</p>
<p>Here is some normal text that is neither boring nor exciting.</p>
<p class="exciting-text">Contributing to MDN is easy and fun.</p>

.exciting-text::after {
  content: " <- EXCITING!";
  color: darkgreen;
  font-weight: bolder;
}

.boring-text::after {
  content: " <- BORING";
  color: darkviolet;
  font-weight: bolder;
}

<span class="ribbon">Look at the orange box after this text. </span>

.ribbon {
  background-color: #5bc8f7;
}

.ribbon::after {
  content: "This is a fancy orange box.";
  background-color: #ffba10;
  border-color: black;
  border-style: dotted;
}

<p>
  Here we have some
  <span tabindex="0" data-description="collection of words and punctuation">
    text
  </span>
  with a few
  <span tabindex="0" data-description="small popups that appear when hovering">
    tooltips</span
  >.
</p>

span[data-description] {
  position: relative;
  text-decoration: underline;
  color: blue;
  cursor: help;
}

span[data-description]:hover::after,
span[data-description]:focus::after {
  content: attr(data-description);
  position: absolute;
  left: 0;
  top: 24px;
  min-width: 200px;
  border: 1px #aaaaaa solid;
  border-radius: 10px;
  background-color: #ffffcc;
  padding: 12px;
  color: black;
  font-size: 14px;
  z-index: 1;
}

<ul>
  <li><a href="#">Introduction</a></li>
  <li><a href="#">Getting started</a></li>
  <li><a href="#">Understanding the basics</a></li>
</ul>

ul {
  font-size: 1.5rem;
  font-family: "Helvetica", "Arial", sans-serif;
}

ul::before,
ul::after {
  display: list-item;
  color: orange;
}

ul::before {
  content: "Start";
}

ul::after {
  content: "End";
}

ul::before::marker,
ul::after::marker {
  color: red;
}