The data URI scheme is a uniform resource identifier (URI) scheme that provides a way to include data in-line in web pages as if they were external resources. This technique allows normally separate elements such as images and style sheets to be fetched in a single HTTP request, which may be more efficient than multiple HTTP request.

In HTML The contenteditable attribute specifies whether the content of an element is editable or not.

Now in your browser url, type in the following and hit enter, you should be able to type in the browser body:

data:text/html, <html contenteditable>

Copy, paste the following code in your browser url and see whats the output
A red dot image, that is base64 encoded

“Keep learning.”