Set An Anchor Link On An Image In Markdown

I use Markdown daily in writing blog posts, README's or answering questions on stackoverflow.com. One undocumented capability of markdown is how to create an image inside an anchor.

This week, I was drafting a post where I wanted to use book covers and have them link to their Amazon product page. I haven't done it before, but I figured, "Hey, this should be simple, I'll check the docs!" 30 minutes after scouring the docs, I realized it wasn't there. So I decided to experiment.

I knew how to create anchors using both inline and reference styles:

<!-- Reference -->
[1]: https://www.bower.io
[My Bower Link][1]

<!-- Inline -->
[My Bower Link](https://www.bower.io)

As well as how to create Images using both inline and reference styles:

<!-- Reference -->
[2]: https://bower.io/img/bower-logo.png
![Bower.io: A Frontend Package Manager. logo][2]

<!-- Inline -->
![Bower.io: A Frontend Package Manager. logo](https://bower.io/img/bower-logo.png)

So I decided to wrap a referenced image within an referenced anchor, making the image the link content:

<!-- The link we want our bower bird to point to -->
[1]: https://www.bower.io
<!-- The image url we want to use for our img tag source -->
[2]: https://bower.io/img/bower-logo.png

<!--
This will compile to two html nodes:
  Anchor:   [linked item][1]: <a href="1">linked item</a>
  image: /i  ![alt text][2]: <img src="2" alt="alt text" />
The image node will be nested inside of the anchor node.
-->
[![Bower.io: A Frontend Package Manager. logo][2]][1]

and voila, here's the output:

If you hover over the Bower bird, you'll see that it is, indeed, a link.