Joomla! since version 2.5 has this cool little features of where you can create a vanity URL or redirect a broken URL in a website to a proper working one.
The component that allows this is called Redirect.
It captures all of the broken links, of 404 errors that appear in the website and allows a website administrator to redirect them to the right or correct pages in a site.
Take this example, joomlabe.at/mailmaner has a little typo in the address, but I've just sent it out to my entire email database list. Since it is in everyone's inbox now, there is nothing I can do in regards to changing the link in the mail out. Instead I can redirect that broken link on the website to the proper page, joomlabe.at/mailmanager, a save the email blast that I just did.
Creating the Redirect
Navigate to the redirect component
Here you will see a list of all the links that have been found missing on your website, e.g. 404 errors. Don't be alarmed if there are hundreds or thousands here. This is common, as search engine spiders and spam bots are constantly trying to crawl websites or hack websites and this is a good indicator of what is happening in those areas.
Filter your view to find the 404 error page that you are trying to redirect or click NEW of the error page doesn't exist.
The next screen will show you the properties of that redirection.
The first field is the URL of the broken link. This could also be the vanity or short URL.
The second field is the URL of where you want the broken link to go.
Next choose ENABLE from the status drop down and click SAVE and CLOSE.
Test your redirection and you should be good to go!
Redirect Plugin Not Activated
In some case you may not have the redirect plugin enabled on your site.
Usually by default this redirect plugin isn't turned on and you may have to turn it on for all of this to work. The redirect plugin does all the hard work in detecting the broken link and working out where it is suppose to go to.
To enable the Joomla! redirect plugin, navigate to Extensions->Plugin Manager
Filter your view down to show just the redirect plugin by typing in 'redirect' in the search field.
Only the redirect plugin should appear. Click on the red X under the column status to enable it. You should now see the green tick and a system message stating that the plugin has been enabled.