When it comes to links, what you see is often not what you will get. Every link is comprised of two parts - the portion that's displayed for you to read, and the actual target.
Many people paste a link into an email and before their very eyes, their mail client 'auto-magically' turns it into a clickable link. That's because the mail client is programmed (depending on the configuration) to recognize tell-tale patterns, such as wwww. or .com.
Unfortunately, this probably perpetuates the notion that what you see is what you get. When it comes to links, however, nothing could be further from the truth.
All links are created by a special tag. This tag tells the Web browser, or email client, or instant messaging app, or twitter app (you get the idea) to hyperlink the text so it becomes clickable.
For example, if I wanted to create a link to 'antivirus.about.com, I would add the following to the HTML code:
<a href="http://antivirus.about.com">antivirus.about.com</a>
This would display as antivirus.about.com and clicking it will lead to antivirus.about.com, the main page of this website. But I could just as easily change the target while keeping the displayed portion intact. For example:
<a href="http://webdesign.about.com">antivirus.about.com</a>
The link still displays as antivirus.about.com but clicking it will now take you to Jennifer Kyrnin's Web Design / HTML site on About.com.
Miscreants exploit this dual nature of links by providing bogus display text - displaying what appears to be a link to a legitimate site, when all the while they are pointing at something entirely different.
The moral of the story? Don't ever take links at face value.