HTML gives us the picture tag, which does a very similar job of the srcset attribute of an img tag, and the differences are very subtle.

You use picture when instead of just serving a smaller version of a file, you completely want to change it. Or serve a different image format.

The best use case I found is when serving a WebP image, which is a format still not widely supported. In the picture tag you specify a list of images, and they will be used in order, so in the next example, browsers that support WebP will use the first image, and fallback to JPG if not:

<picture>
<source type="image/webp" srcset="image.webp">
<img src="image.jpg" alt="An image">
</picture>

The source tag defines one (or more) formats for the images. The img tag is the fallback in case the browser is very old and does not support the picture tag.

In the source tag inside picture you can add a media attribute to set media queries.

The example that follows kind of works like the above example with srcset:

<picture>
<source media="(min-width: 500w)" srcset="dog-500.png" sizes="100vw">
<source media="(min-width: 800w)" srcset="dog-800.png" sizes="100vw">
<source media="(min-width: 1000w)" srcset="dog-1000.png"	sizes="800px">
<source media="(min-width: 1400w)" srcset="dog-1400.png"	sizes="800px">
<img src="dog.png" alt="A dog image">
</picture>

But that’s not its use case, because as you can see it’s much more verbose.

The picture tag is recent but is now supported by all the major browsers except Opera Mini and IE (all versions).