What does this mean? Let me explain: images (gifs, jpegs, pngs) are usually stored in binary format, and cannot be represented using textual characters. By encoding the file data into base64 format, it is possible to represent the image with textual characters. The file size is a little bigger, but for small images the difference isn't that great, and the text can be compressed.
How is it done? First the image needs to be converted into base64. I use a command line tool called, what else, base64. It goes like this:
The result looks something like this:
To use this data in HTML, the image tag looks like this: