It's an interesting question because it has been generally most people use the term virus when infected by malicious code (malware).
In dealing with malware in the customer does not want to get too hung up if the customer insists she got a virus (although possibly worm), which is important only help resolve the issue first. Instead busy arguing and did not solve the problem
By definition if we talk about malicious code term used is malware (malicious software / software rogue / malicious code). Because malware is malicious code, it includes worms, trojans, viruses, spyware / adware, rootkits, bots, exploits, and other backdoor.
But not too long so we discuss the most general ones: viruses, worms, spyware, trojans as you ask. And the bit about the vulnerability (vulnerability), patches and service packs.
Virus
Malware to infect computers that need assistance / intervention of a third party (usually a man's) to run itself and can not be run automatically infect your computer. So that people would run itself, falsifying virus itself as well as the program. Doc,. Jpg or folder when clicked will run the virus.
In many cases, in order to further convince people to click on her, viruses falsify itself (icon, extension) as pornographic images, file crack or anything else that will attract people to click.
Malware
Malicious software is software created for malicious purposes. Basically, malware is software / computer program, which distinguishes malware software is a goal and an adverse action such as changing the victim computer (removing, stealing or hiding) data, consume bandwidth or other resources without the permission of the owner of a computer or other adverse action.
Worm
Malware that can automatically infect a computer without the aid of a third party. So once the worm is on your computer / network, it will automatically spread itself to other computers without the help or even without being prevented by the owners of the other computers in the network.
So if the security hole exploited / used by the worm to spread itself automatically already patched (patch) then the worm becomes memble and do not have the ability to infect the system again. So in terpatch system, the virus infects the system even easier than the worm.
Surely there's a question, if the worm can spread itself automatically, then why not make a worm all, why even create viruses that need help to activate him.
So that the worm can automatically infect your computer it must exploit security holes (vulnerabilities) software (can Games, Windows, Office, Adobe Acrobat or any software that is generally popular target).
Trojan
Just like the movie Troy, Trojan is a Trojan horse that will pretend to be useful both crack programs, games or other programs that secretly you install itself on the system and carry out spying activities such as stealing data, keystroke recording and send to the address specified by the manufacturer.
Spyware
Like the movie 007, spyware is a program to spy on the victim computer. At first the spyware is created to spy on computer users profile and one of its utilization is showing adware (advertising software viewer / ad) in accordance with the profile / interests of computer users where each time the ad appears on the computer which will provide direct financial benefits for manufacturers of these adware ( pay per click).
After it was suppressed, then circulated rogue antivirus (fake antivirus) which is an adware metamorfisis originally hoped to profit financially from the advertiser when appearing on the computer which, because of the many ad-blocker so he developed into a rogue antivirus which if successfully active on the computer which he will frighten his victims by displaying fake messages as if the victim computer is infected by a lot of harmful malware and messages designed to annoy and can only be cleared if you buy an antivirus application on the link provided.
OOT
To prevent exploitation of vulnerabilities (vulnerability) software vendor issued a patch (patch) every time some security holes. A collection of patches that are called 'service pack', so now you know why every time install OS should install 'service pack'.
In the latest OS patch system vulnerabilities which happens automatically every time the computer starts and connects to the internet it checks the latest patches and automatically updates so avoid exploitation.
One of the main objectives is to ensure that vulnerabilities and other bugs found during previous years can be patched everything and computers running safely and smoothly jaya and browse the network / internet.
