URL shorteners are in our lives since 2001 (1), making it easier to share long URLs through instant messaging, social media platforms and even IRC. Even though they were a huge help for people using chat systems in which clickable URLs were not natively supported (like early massively multiplayer online games), they became an indispensable part of our lives with the rise of Twitter.
However, it is not all sunshines and rainbows and beautiful, short links with these services as they have downsides as well. One of the many handicaps of heavily using these services is that they make every link posted through them reliant on the URL shortening service as well as the target web page. While we are having enough trouble keeping stuff online despite the costs of doing so going steadily down (Jeremy Keith’s post on the day Geocities died perfectly reflects my feelings on this matter (2), having to rely on one more service to be able to look back on what we have posted or viewed greatly reduces the usability of the archival abilities of the tools and services we use day to day.
Another downside of URL shorteners is the security threats they pose. While most of the online population learned not to open every link sent their way one way or the other (rickroll link), it is very important to remember that these services are essentially masking any URL fed to them and they can be used very effectively for phishing and similar malicious activities (3). Even though major URL shortening services let users preview their URLs (4), you know how many of these links you previewed before opening them.
All in all, URL shorteners are a mixed bag we have come to rely on and there is no indication that they are going away soon. What we can do is simply being careful with them.