Link

Protocol Handlers

The mailto: URL scheme is used to create links that should open the user's email client with a prepopulated email address as the receiver. Some mail clients also support passing CC, BCC, subject, and/or body. [MDN, RFC 6068]

The tel URL scheme is used to open a (phone) caller application with the specified phone number [RFC 3966, css-tricks.com]. Not all browsers and/or operating systems support this scheme, and there is currently no (reliable) way to feature detect it [stackoverflow.com].

Some operating systems may support more protocol handlers [developer-mdn.apple.com].

Custom protocol handlers can be defined with registerProtocolHandler() [MDN].

Text Fragments

Similar to anchor links, text fragments allow linking to a certain location within a page. But unlike anchor links, these do not rely on the author to put anchors in the page's code. Instead, any text fragment can be used as a locator. Text fragment links start with #:~:text= and include textStart with optional textEnd/prefix/suffix. [MDN]

Browser's may highlight the section that the text fragment linked to. The website's author can use the ::target-text pseudo-element to change that styling. [MDN, spec]

PDF Fragment Identifiers

Links to PDF documents can be extended with special fragment identifiers. For example, linking to document.pdf#page=42 should scroll to the PDF document's page 42. Further identifiers like zoom or nameddest are also available. [RFC 8118, pdfa.org]

Not all features are available in all browsers [pdfa.org].