Removable media such as cds, floppy disks, usb keys that are infected and used in another system can carry the virus and infect the other machine. If you computer is infected with a virus you will need to remove the virus as soon as possible otherwise it can infect the system completely and spread to others. If a computer is infected by a computer virus the computer needs to be scanned by virus scanning software. When surfing the internet most likely you been infected with a Trojan, virus, or some type of spyware, according to many virus detection agencies, the unprotected PC is infected on average within 20 minutes of normal internet usage. Many systems get infected every day, you must take safety measures or your system might get infected, and the virus might corrupt your data on your system. A Computer Worm is a self replicating program, the first worm to gain wide attention was the Morris Worm this infected a large number of computers and earned its writer 400 hours of community service and over $10000 in fines. When a virus infects you computer it can replicate itself, use up system resources, allow a user remote access, record keystrokes to the infected computer, it also has the ability to destroy personal data.

You must take precautions because when you download it may contain spyware, adware or viruses, spyware and adware can collect personal data, record your browsing habits and no more about you. Ad and Spyware are programs that are automatically installed on your computer.

When your computer is infected with a virus they are designed to alter your normal computer functions and spyware infections are used to spy on you, one way they do this is by recording your personal information. Many times adware, viruses and spyware find what is called a "back door" to install and replicated itself you in your computer.

Downloading may sometimes cause error on the system or the entire computer system may crash. Many spyware or viruses are downloaded when downloading software and music. Many viruses can lay dormant without you knowing this, since you don't know it is there it can attack at any moment when least expect it, it could attack when typing a report and downloading important. Whether you have learned your lesson from a past experience or not, try not to download unwanted files or open email messages sent to you by people you don't know. Many people do all of this without any real understanding of just how vulnerable they are each time they are on the internet. Try to take precautions, find reputable software and install it to protect your system. There is free software on the web that will protect your system.

About the Author

David Marc Fishman is the owner of howtopcguru.com. Protect your pc against adware