Some of the very few, but most commonly used are:
• <anything>.com
• <anything>.exe
• <anything>.txt.vbs
There are no reasons whatsoever for the user to use any of these formats, unless their main priority is to infect the receivers computer. Period.
I can also assure you there is no reason a file should have a double extension. But that does'nt stop (ignorant) people falling victim who have no idea how to tell if a file has a double extension or not.
Whether you click a link in an e.mail, or click a link on a site, as simple as that.
And after the Trojan installs itself on your computer, it will then simply send a message from your computer to the hacker telling him the following information.
Username: (A name they call you)
IP Address: (Your IP address)
Online: (Your victim is online)
And it doesn’t matter if you are on dial up. The 'potential hacker' will automatically be notified when you log on to your computer. With that information, it is not a task to gain access to ones comp with a few clicks.
Oh, and critique with a respectful manner, or not at all.