URL shortening
URL shortening is a technique on the World Wide Web in which a Uniform Resource Locator (URL) may be made substantially shorter and still direct to the required page. This is achieved by using a redirect which links to the web page that has a long URL. For example, the URL "https://example.com/assets/category_B/subcategory_C/Foo/" can be shortened to "https://example.com/Foo", and the URL "https://en.wikipedia.org/wiki/URL_shortening" can be shortened to "https://w.wiki/U". Often the redirect domain name is shorter than the original one. A friendly URL may be desired for messaging technologies that limit the number of characters in a message (for example SMS), for reducing the amount of typing required if the reader is copying a URL from a print source, for making it easier for a person to remember, or for the intention of a permalink. In November 2009, the shortened links of the URL shortening service Bitly were accessed 2.1 billion times.[1]
Other uses of URL shortening are to "beautify" a link, track clicks, or disguise the underlying address. This is because the URL shortener can redirect to just about any web domain, even malicious ones. So, although disguising of the underlying address may be desired for legitimate business or personal reasons, it is open to abuse.[2] Some URL shortening service providers have found themselves on spam blocklists, because of the use of their redirect services by sites trying to bypass those very same blocklists. Some websites prevent short, redirected URLs from being posted.
Purposes[edit]
There are several reasons to use URL shortening. Often regular unshortened links may be aesthetically unpleasing. Many web developers pass descriptive attributes in the URL to represent data hierarchies, command structures, transaction paths or session information. This can result in URLs that are hundreds of characters long and that contain complex character patterns. Such URLs are difficult to memorize, type out or distribute. As a result, long URLs must be copied and pasted for reliability. Thus, short URLs may be more convenient for websites or hard copy publications (e.g. a printed magazine or a book), the latter often requiring that very long strings be broken into multiple lines (as is the case with some e-mail software or internet forums) or truncated.
On Twitter and some instant messaging services, there is a limit to the number of characters a message can carry – however, Twitter now shortens links automatically using its own URL shortening service, t.co, so there is no need to use a separate URL shortening service just to shorten URLs in a tweet. On other such services, using a URL shortener can allow linking to web pages which would otherwise violate this constraint. Some shortening services, such as goo.gl, tinyurl.com, and bit.ly can generate URLs that are human-readable, although the resulting strings are longer than those generated by a length-optimized service. Finally, URL shortening sites provide detailed information on the clicks a link receives, which can be simpler than setting up an equally powerful server-side analytics engine, and unlike the latter, does not require any access to the server.
URLs encoded in two dimensional barcodes such as QR code are often shortened by a URL shortener in order to reduce the printed area of the code, or allow printing at lower density in order to improve scanning reliability.
Registering a short URL[edit]
Some websites create short links to make sharing links via instant messaging easier, and to make it cheaper to send them via SMS. This can be done online, at the web pages of a URL shortening service; to do it in batch via bulk upload with tools like CSV importer or on demand may require the use of an API.
A few well-known websites have set up their own URL shortening services for their own use – for example, Twitter with t.co,[3] Google with g.co,[4] and GoDaddy with x.co.[5]
Expiry and time-limited services[edit]
While many providers claim their shortened URLs won't expire for as long as the service is provided, they may decide to discontinue the service at any time.
A permanent URL is not necessarily a good thing. There are security implications, and obsolete short URLs remain in existence and may be circulated long after they cease to point to a relevant or even extant destination. Sometimes a short URL is useful simply to give someone over a telephone conversation for a one-off access or file download, and no longer needed within a couple of minutes.
Some providers offer expiration on shortened URLs. This may include URLs that expire after a certain amount of time, on a certain date or after a certain number of usages.
A Microsoft Security Brief recommends the creation of short-lived URLs, but for reasons explicitly of security rather than convenience.[9]
Advantages[edit]
The main advantage of a short link is its brevity. Depending on the transcription used, it might be more easily communicated and entered without error. To some extent it can obscure the destination of the URL; this may be advantageous, disadvantageous, or irrelevant.