In computers, to execute a program is to run the program in the computer, and, by implication, to start it to run. In usage, people run programs and systems execute them. That is, a system user asks the system to run the program (or sets it up so that this happens automatically at a certain time) and, as a result, the system executes the program. Typically, we don't say that a program is executing; we say that it is running.
An executable is a file that contains a program - that is, a particular kind of file that is capable of being executed or run as a program in the computer. In a Disk Operating System or Windows operating system, an executable file usually has a file name extension of .bat, .com, or .exe. An executable file or a group of them are sometimes referred to as binaries as in "I'll download the binaries to you" since the file format of an executable is a solid sequence of binary values that cannot be easily read by anyone (unlike that of, for example, an ASCII text file which can be easily examined for information as it travels from one computer to another).
A file whose name ends in ".exe" is really a program that when "opened" - that is, selected by putting your mouse over the file name and then initiated by double-clicking your mouse, for example - causes the operating system to run the program. Users who receive an .exe file as an e-mail attachment should always be sure that the file comes from a trusted source and is not, in fact, a computer
A destructive program that masquerades as a benign application. Unlike viruses, Trojan horses do not replicate themselves but they can be just as destructive. One of the most insidious types of Trojan horse is a program that claims to rid your computer of viruses but instead introduces viruses onto your computer.
The term comes from a story in Homer's Iliad, in which the Greeks give a giant wooden horse to their foes, the Trojans, ostensibly as a peace offering. But after the Trojans drag the horse inside their city walls, Greek soldiers sneak out of the horse's hollow belly and open the city gates, allowing their compatriots to pour in and capture Troy. [Return]
Viruses: A computer virus is a program designed to spread itself by first infecting executable files or the system areas of hard and floppy disks and then making copies of itself. Viruses usually operate without the knowledge or desire of the computer user. [Return]
[For a more detailed explanation of computer viruses]
Worms: A program or algorithm that replicates itself over a computer network and usually performs malicious actions, such as using up the computer's resources and possibly shutting the system down. [Return]
Browser: Short for Web browser, a software application used to locate and display Web pages. The two most popular browsers are Netscape Navigator and Microsoft Internet Explorer (AOL uses their own version of Microsoft Internet Explorer). Both of these are graphical browsers, which means that they can display graphics as well as text. In addition, most modern browsers can present multimedia information, including sound and video. [Return]
Kak is a worm virus that spreads through HTML coding in e-mail and newsgroup postings. The dangerous thing about Kak is that you do not need to open any attachments to become infected - just viewing a message is enough. This is because the virus code is contained within some HTML code (invisible under normal settings) which runs without you knowing in Outlook and Outlook Express. Yep, you guessed it - it's the Microsoft programs at risk.
Once activated, the virus does several things. First, it creates a file in your windows directory called kak.htm, which contains the code that infects computers. This file is then set in Outlook to be your default signature, so the virus is attached to all your outgoing messages (but only those sent in HTML format).
Your registry is also altered, and a file called kak.hta may also be placed into your startup group (in the Start menu). Another .hta file is also created in your Windows or Windows/System directory - it's name is a series of 8 seemingly random letters and numbers derived from your Outlook identity code. Finally, your old autoexec.bat is copied to ae.kak and the existing version has some lines added to run the kak code on startup (which is why it's hard to get rid of it). [Return]