Deep Linking
Linking straight to a specific page or item rather than a site's front door, once fought over in court and now a feature that apps and web apps must work to support.
Deep linking is linking to a specific page or item inside a site or app rather than to its home page. On the web it's just linking, since any page with an address can be linked to; see URL. The term exists because some publishers objected, and because apps made it hard again.
In the late 1990s, several companies argued that linking past their home pages was unfair. The home page carried the ads and the branding, and a deep link let visitors skip both. In 1997 Ticketmaster sued Microsoft for linking straight to event pages on its site; the case settled in 1999. In a later case against another ticket site, a federal court in California ruled in 2000 that deep linking alone wasn't copyright infringement, since nothing was copied. A Scottish newspaper dispute in 1996 had raised the same question earlier. Most of the web settled on the view that a public page can be linked to, and publishers who object can require logins instead.
Deep links are what make the web useful as a reference. Citations, search results, and shared articles all point inside sites. That only works if addresses stay stable, a principle Tim Berners-Lee stated in 1998 as "cool URIs don't change".
Web apps can break it. Early Single-Page Application designs changed the screen without changing the address, so a bookmarked or shared link always opened the start screen. Browsers later added a way for scripts to update the address bar, letting apps restore deep links. A good test is whether a link copied from the address bar opens the same view in a fresh window.
Mobile apps had the same problem at a larger scale, since an app screen has no address at all. Apps first registered custom schemes, which any other app could also claim. In 2015 Apple and Google introduced verified links, called universal links on iOS and app links on Android: the site publishes a file proving it owns the app, and ordinary web addresses then open the matching app screen if it's installed and the website if not. Deferred deep links remember the destination through an app install, so a new user lands where the link pointed instead of on a welcome screen.
Deep links are also an attack surface. A link that opens an app screen with parameters can trigger actions or carry a malicious redirect (an Open Redirect), and look-alike links are a staple of Phishing.
Linking to a page is different from displaying a file from someone else's server; see Hotlinking. Sharing a deep link in a chat usually shows a preview built from the page's metadata; see Open Graph.
See also3
Tabs
A row of labels that switch between panels of content occupying the same space, borrowed from paper folder tabs, suited to parallel sections viewed one at a time, and governed by a specific keyboard pattern.
Design & Interface12 connections
Search Engine Optimization
Making content discoverable through search, most of which is ordinary quality work.
Data & Content29 connections
State Management
How a front-end application keeps track of the data that changes as people use it, and decides where each piece lives, from local component state to global stores to server caches.
Web Platform12 connections
Linked from8
- HotlinkingWeb Platform
Displaying an image or file on your page straight from someone else's server, so they pay for the traffic, which sites block by checking where requests come from and which courts have treated differently from copying.
- Open GraphWeb Platform
The meta tags a page uses to describe its own preview card when a link is shared, how chat apps and social networks fetch them, and why a preview shows only what the page claims about itself.
- Open RedirectWeb Platform
A page that forwards visitors to whatever address a URL parameter names, letting attackers borrow a trusted domain to launch phishing or steal sign-in tokens, and the narrow ways to fix it.
- Progressive Web AppWeb Platform
A website that can be installed like a native app, launched from the home screen in its own window and used offline, built from a manifest, a service worker and HTTPS.
- Search Engine OptimizationData & Content
Making content discoverable through search, most of which is ordinary quality work.
- State ManagementWeb Platform
How a front-end application keeps track of the data that changes as people use it, and decides where each piece lives, from local component state to global stores to server caches.
- TabsDesign & Interface
A row of labels that switch between panels of content occupying the same space, borrowed from paper folder tabs, suited to parallel sections viewed one at a time, and governed by a specific keyboard pattern.
- URLWeb Platform
The address format that names every resource on the web, its parts from scheme to fragment, and why parsing one correctly is harder and more security-relevant than it looks.