You might be used to inserting web hyperlinks into documents or when composing emails (click Edit > Add Link and type the address). Whenever anybody clicks the link, they’ll visit the site you specified, just like in a web page.
In addition to links to websites, MacOS lets you create app-specific links. For example, you could include a link in a mail message that, when clicked, will start within the Messages app an instant messaging conversation with somebody. You could create a link in a document that, when clicked, looked up a particular word in the Dictionary app.
To create a link in a TextEdit document or new mail window, highlight the text you want to turn into the link, and click Edit > Add Link, or hit Command+K.
Then look to the following list for what to type into the Create Link dialog box.
http://—You can insert links to web pages by simply typing the address, including the http:// component. For example, typing http://keirthomas.com will create a link to that site.
imessage://—This will start a Messages conversation within the Messages app. For example, typing imessage://07912345678 will open Messages and attempt to start an iMessage conversation with that phone number – or send an SMS if you have Handoff enabled. You can also specify IM handles: if you have a Yahoo buddy whose handle is johnsmith, you could create the following link: imessage://johnsmith. This assumes you’ve configured Messages to log onto your Yahoo account, of course.
facetime://—This will start a FaceTime conversation within the FaceTime app. For example, facetime://firstname.lastname@example.org will attempt to start a FaceTime conversation with the individual whose FaceTime account is registered to that address. Apple IDs and phone numbers can also be specified, although as with iMessage, the phone number should be typed without any spaces or symbols in it.
dict://—This will cause the Dictionary app to start and look up a particular word. For example, dict://epicurean will open Dictionary with the word definition for Epicurean displayed, as if it had been typed into the search field.
vnc://—This will open a screen-sharing session with whatever address is specified, although the user will still have to click the Connect button in a dialog box that appears when the Screen Sharing software starts. vnc://macbook will attempt to start a screen-sharing session with the computer whose network name is macbook.
x-man-page://—This will open the man page for the specified term within a Terminal window. For example, x-man-page://sharing will open the man page for the sharing command.
When used without any specified address (that is, if you simply type imessage:// or facetime:// in the link dialog box), the apps will be activated when the link is clicked, as if the user has clicked their app icon in the Dock.
It’s also possible to insert other, typical URLs that are used in web pages, such as mailto://, ssh://, and telnet://.