Someone asked me about this in a DM on Twitter. I was going to just tweet back some links, but the explanation is going to take more than 140 characters.
What is a shortened URL?
A shortened URL takes a really long URL, like https://community.emc.com/community/connect/emcpp?view=overview and smooshes it into a URL with fewer characters, like http://bit.ly/9xdDGT . Click on either URL, they will go to the same place. Shortened URLs are really important when every character in a message counts (like with Twitter).
Shortened URLs work by redirecting HTTP requests. If you want to know on the nitty gritty technical details, this Stack Overflow page is a good place to start.
How do I know if the shortened URL will not take me to a bad place?
If you only look at the shortened URL, you DON’T know you won’t be going to a bad place. Like this: http://bit.ly/9VpMNu
So what can you do to protect yourself?
Know your sources
If you don’t know the source well enough, or don’t trust the source for any reason, DO NOT CLICK ON THEIR SHORTENED URLs. I’ll explain how to test these URLs in a minute.
So what if you really know and/or trust the source? Should you click on any shortened URL he or she posts?
Well, no not necessarily. If my fellow blogger Storagezilla started sharing shortened URLs and said they were about the best place to get your nails done in Ireland, I’d probably email him to make sure he was ok, and to let him know his account had been compromised.
Your first line of defense is trust. If you don’t know them or trust them, don’t click. If you trust them but the links seem out of character, don’t click.
Ways to find out the real URL behind the shortened URL
- Google
Google the Shortened URL. This won’t work if the shortened URL was just created. - Go to the Shortened URL site
Most of the shortened URL services will have a way to examine the target page of the shortened URL. Go to their site and check for that service - Get a Browser plug-in
There are plug-ins you can get for your browser that will expand the shortened URL when you hover over it with your mouse. For example, check out the Expand URL add-on for Firefox. - Use a long URL website
Use a site like http://longurl.org/ to find the target URL of the shortened URL.
If you have more methods, please add them in the comments. The idea behind shortened URLs is good, but you do need to use a little common sense. Let’s be careful out there!