There could be many reasons to want to use a URL redirect. For example the normal www.yournamexx.com is the site most people would associate with a website. However the version http://yournamexx.com is sometimes used. To the search engines these are two different sites. A redirect can be used to point one to the other, depending on which URL the site is actually residing on.
Many who purchase domain names purchase names with the same name but different extensions. For example you may have purchased www.qqzwxx2.com, www.comxx2.net and www.qqzwxx2.org. If you want to forward the .net and .org versions of the name to your actual site on www.comxx2.com then a redirect will do that. A URL redirect is sometimes called URL Forwarding or domain forwarding.
For Internet marketers a prime use of URL redirects is to hide the sometimes long hideous curls of many affiliate links. These long urls with many parameters usually give away the fact that the url is an affiliate url and some visitors will not click them. Other unscruplous persons may delete the parameters in the long address and eliminate any possible commission you could receive
Since the Internet revolution the dot com name has taken hold. However many people have registered dot net, dot org, and now there are over 100 different extentions available. But dot com names are most common and even casual conversation when one mentions websites a dot com name is usually assumed. If you are one of the ones forced to get another extention because your preferred dot com name was already taken then a UIIR Smart URL Redirect can give you a nice surrogate url address that is a dot com name.
Short concise urls are more professional looking. Even if you have a url such as www.slylikearedfox.com you can always have an additional url such as //uiir.com/r/slyfox as another way to reach your website.