Link-based sharing is a distribution model where the URL itself acts as the access key. If a service is designed this way, anyone who has the link may be able to view the content without logging in or being separately approved. That makes the link both a locator and a permission token.
This matters in cyber security because leaked or guessed URLs can expose private files, images, or messages. Attackers may harvest links from logs, emails, browser history, shared documents, or metadata, then use them to browse content that was meant to be “private but shareable.” Defenders reduce risk by using long, unguessable identifiers, adding authentication, expiring links, limiting access scope, and treating link metadata as sensitive. In a breach, exposed IDs or URL components can be as valuable as the content itself if they help reconstruct access paths.