A dynamic URL QR code encodes a shortened URL (an intermediary URL) rather than the final destination URL. This means the QR code itself never changes, yet the page it leads to can be updated at any time through the URL shortening service's dashboard.
With a static QR code, the encoded URL is permanent. If you need to point it somewhere else, you must regenerate the QR code and reprint every piece of material that carries it. A dynamic QR code eliminates that cost entirely - just update the redirect target and every already-printed code instantly points to the new page.
Use cases are plentiful. A restaurant can rotate seasonal menu pages behind a single QR code on every table. An event organizer can switch from a pre-event landing page to a post-event archive. A product manufacturer can refresh campaign pages on packaging without recalling stock. In each scenario, the printed material outlasts any single link destination.
The cost savings scale with volume. If a batch of 10,000 flyers contains a QR code pointing to the wrong page, a static code means reprinting the entire run. A dynamic code means a 30-second edit in a dashboard. For large-scale campaigns the difference can be tens of thousands of dollars.
Technically, this is simply the standard redirect feature that any URL shortening service provides. You encode a short URL such as "https://miji.be/abc123" into the QR code, then manage where that short URL redirects. Click analytics come along for free, giving you scan counts, geographic distribution, and device breakdowns. You can find related books on Amazon.