Did you know that you don’t have to link to an external image file when using an <img> element in HTML, or declaring a background-image in CSS? You can embed the image data directly into the document with data URIs.

Why would you do this?

The biggest reason: it saves HTTP Requests. Other than pure document size, this is the #1 factor concerning how fast a page loads. Less = better.

The format, to be specific:

data:[<mime type>][;charset=<charset>][;base64],<encoded data>

li {
  background:
    url(data:image/gif;base64,R0lGODlhEAAQAMQAAORHHOVSKudfOulrSOp3WOyDZu6QdvCchPGolfO0o/XBs/fNwfjZ0frl3/zy7////wAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACH5BAkAABAALAAAAAAQABAAAAVVICSOZGlCQAosJ6mu7fiyZeKqNKToQGDsM8hBADgUXoGAiqhSvp5QAnQKGIgUhwFUYLCVDFCrKUE1lBavAViFIDlTImbKC5Gm2hB0SlBCBMQiB0UjIQA7)
    no-repeat
    left center;
  padding: 5px 0 5px 25px;
}

<img width="16" height="16" alt="star" src="data:image/gif;base64,R0lGODlhEAAQAMQAAORHHOVSKudfOulrSOp3WOyDZu6QdvCchPGolfO0o/XBs/fNwfjZ0frl3/zy7////wAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACH5BAkAABAALAAAAAAQABAAAAVVICSOZGlCQAosJ6mu7fiyZeKqNKToQGDsM8hBADgUXoGAiqhSvp5QAnQKGIgUhwFUYLCVDFCrKUE1lBavAViFIDlTImbKC5Gm2hB0SlBCBMQiB0UjIQA7" />

How do you get the code?

Use this online conversion tool. It’s the nicest one I have found. Here’s a drag and drop one.

Save my day: css-tricks.com