One of the biggest slowdowns of a PC is caused by viruses, adware or spyware as it's often called. Before you can benefit from any other optimization tips or improvements you really need a system relatively free from those pests.

A virus is a piece of malicious software code written to cause some kind of damage to a computer system or network or even the Internet itself. Viruses spread, similar to their biological namesake, from one machine to another and can
spread havoc wherever they go. They are most commonly spread by sharing files with others or through email attachments where they can be set up to send themselves to all the addresses in your email address book.

Adware is usually downloaded and installed along with some other program without your knowledge and unlike a virus doesn't spread by itself. Very often you click "OK" without reading the terms and conditions and by doing so you
agree to have the files installed. An example is you see a "free" program on offer that you think might be useful and download it without thinking. Even some anti-spyware programs install adware and the website earns money from the ads that are clicked on.

The catch is that the extra files introduced are used to determine things like your surfing habits and the data is used to serve up popup ads or redirect your browser to a page other than the one you wanted. Some of the programs can be used to install key-loggers which can send back information about passwords and bank details etc. Adware is not a security problem it is more an annoyance especially when you have ten different programs trying show ads. The amount of computer resources it uses up slows your system to a crawl.

Spyware is more malicious and evil intentioned and is designed to steal something from you. It can be downloaded by visiting the wrong types of websites or along with other files the same way as adware. Spyware can often be hard to remove as it can continually recreate itself and hide somewhere on your hard drive.

Programs such as trojans can be used to allow access to hackers at a later date. From the story of the Trojan horse where the Greeks hid inside the wooden horse left as a peace offering and were wheeled in to the fort by the Trojans themselves. Then at night the Greeks crept out of the horse and opened the gates and let the enemy in. Trojans and adware unlike viruses don't spread themselves.

It is wise to run more than one spyware checker as no one system gets rid of them all. You can never be certain you have every one removed because new ones may not have been discovered and the Spyware program doesn't recognize it yet. I use the two free ones "Spybot" and "Adaware" and I also use "Norton Anti-virus".

Sometimes people say to me "doesn't my anti-virus software remove spyware"? Well the answer is most don't and even if it does I always find a specialist product works best. Beware also of bogus spyware scanners available on-line
which actually install their own spyware once they have removed their competitors. Sometimes you run a free scan and it finds all sorts of nasties but you will have to sign up and pay to remove them. I have even seen it that they find things that don't exist or try to frighten people into believing they have lots of spyware when all they have are advertising cookies.

Cookies are small text files that websites leave on your system so that when you return they can customise the page that loads or they can count you as a returning visitor. They are harmless and most of them are useful. They can be
easily removed by deleting them in your browser settings. So you need to be running a suitable and up to date antivirus program and one or more Spyware checkers.

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