The for accessibility required `caption` element in HTML tables

I'm sitting at the airport in Bangkok right now (yeah vacation!!!) and am reading an article by Adrian Roselli on tables regarding accessibility.

It can not be that hard to build an accessible table. It's just the table element including other th, tr and td elements, right?

Not quite... The article goes into beautiful detail on what it means to build an accessible table, and in the first few paragraphs of it, it already included something that was new to me – the caption element in tables.

<table>
  <caption>Populations of cities</caption>
  <thead>
    <tr>
      <th>City</th>
      <th>Population</th>
    </tr>
  </thead>
  <tr>
    <!-- ... -->
  </tr>
</table>   

caption is one element you don't see "in the wild" very often. The spec defines it as follows:

[...] the first element child of a table element.

The caption element represents the title of the table that is its parent, if it has a parent and that is a table element.

Defining a title and some additional information for a table makes total sense, and more surprising than its rare usage is only that the caption element even has its own mention in the techniques for WCAG 2.0. 😲

That said, my next table definitely includes a caption element.

Edited: As Eric Eggert pointed out there are also other ways to label a table.