There are several reasons to use URL shortening. The free hosting space provided by access Internet Service Providers for its customers may generate an aesthetically unpleasing address. Some web developers on mainstream sites tend to pass descriptive attributes in the URL to represent data hierarchies, command structures, transaction paths or session information and this often results in a URL that contains a large number of characters, is awkward to reproduce and impossible to remember. Copying a URL that is hundreds of characters long can only really be successfully done by copy-and-paste. Trying to type one by hand will be time-consuming and may result in errors. Thus a tiny url is more useful to write in an e-mail message or an internet forum post.
On Twitter and some instant-messaging services, there is a limit on the total number of characters that can be used in a message. Using a URL shortener can make it easier to include a URL within a short message. Some shortening services, such as goo.gl can generate URLs that are human-readable, although the resulting strings are longer than those generated by a length-optimized service. A QR Code that stores a URL can be more readable by using a URL shortener to minimize the length of the URL it encodes.citation needed Finally, the URL shortening sites provide detailed information on the clicks the link receives, this can be simpler than setting up an equally powerful server side analytics engine.
An increasing number of websites are registering their own tiny url to make sharing via Twitter and SMS easier. This can normally be done online, at the web pages of a URL shortening service. Short URLs often circumvent the intended use of top-level domains for indicating the country of origin; domain registration in many countries requires proof of physical presence within that country, although a redirected URL has no such guarantee.
Short URLs, although making it easier to access what might otherwise be a very tiny url or user-space on an ISP server, add an additional layer of complexity to the process of retrieving web pages. Every access requires more requests (at least one more DNS lookup and HTTP request), thereby increasing latency, the time taken to access the page and also the risk of failure, since the shortening service may become unavailable. Another operational limitation of URL shortening services is that browsers do not resend POST bodies when a redirect is encountered. This can be overcome by making the service a reverse proxy, or by elaborate schemes involving cookies and buffered POST bodies, but such techniques present security and scaling challenges, and are therefore not used on extranets or Internet-scale services.
Shortened internet links typically use foreign country domain names, and are therefore under the jurisdiction of that nation. Libya, for instance, exercised its control over the .ly domain in October 2010 to shut down vb.ly for violating Libyan pornography laws. Failure to predict such problems with URL shorteners and investment in URL shortening companies may reflect a lack of due diligence.
The convenience offered by URL shortening also introduces potential problems, which have led to criticism of the use of these services. Short URLs, for example, will be subject to linkrot if the shortening service stops working; all URLs related to the service will become broken. It is a legitimate concern that many existing URL shortening services may not have a sustainable business model in the long term. This worry was highlighted by a statement from tr.im in August 2009 (see above).9 In late 2009, the Internet Archive started the “301 Works” projects, together with twenty collaborating companies (initially), whose short URLs will be preserved by the project.9 The URL shortening service ur1.ca provides its entire database as a file download, so if its website stops working, other websites may be able to provide ways to correct broken links to URLs shortened with its service.