Not sure this is the absolute minimum. The HTML5 spec is big and browsers are tolerant. Close enough.

NOTE:

This post is outdated. Please see Minimal HTML5 Document With Latest Version of jQuery from CDN.

Minimal HTML document that loads the most recent version of jQuery version 1.X. There’s no way at the moment to designated the latest version, period.

NOTE: Oh Yes There Is

JQuery can indeed do that for you. Minimal HTML5 Document With Latest Version of jQuery from CDN.

Try it now

Here’s a complete HTML file with jQuery actually doing something. Clicking the button shows or hides a div containing the text “hello, world.”