A lot. Lets be clear about this. There are a load of things out there; some quite innocent (jokes almost), others used to build up a marketing profile on you (still quite insidious if you think about it); and, plenty out there which can do you real harm.

So, lets have a quick look at the usual suspects.

First up are malicious web scripts and code. These are bits of code which are designed to make your life hell. They might come in the form of ActiveX controls and they have a number of tricks, including installing spyware on your system, stealing personal information and deleting files.

ActiveX controls are beloved by Internet Explorer, and only them, so, if you don’t want to take the risk, upgrade your Internet Explorer version (7 and 8 have better safeguards), or use a different browser such as Firefox.

Now, next in the line-up are for some quite innocent little things. Cookies are more sneaky, than dangerous, and without them, many of the sites you might use on a regular basis, wouldn’t be so convenient. But bear in mind that cookies are effectively trackers of your behaviour and choices. And they are often used to report back to their owners a lot of information about you. So, if this sounds intrusive, don’t encourage them.

Next are pop-ups. These might sound like innocent critters, but avoid them. Pop-ups are little ads which can quickly clutter up your computer as they appear and disappear at their choosing. And although many of them might be innocent, quite a few are used as carriers of nastier things, such as spyware, so get rid of them pronto. Use a pop-up blocker, or, if you’ve got Windows XP with Service Pack 2, or Vista, then they have pop-up eradicators.

Malware has a wide range of definitions and sub-groups, although what makes this subject confusing, is that different groups of people use different labels and explanations. But, generally, the main types of malware are: spyware, adware and home page hijackers (or browser hijackers).

Spyware literally spies on your computer. It might do that covertly, or overtly, creating pop-ups, or downloading so many applications on your computer, that it slows your machine down to a snail’s pace. It also grabs usernames, password and bank details, sending therm back to its creator.

Adware is often the price you pay for free software applications. But it’s simply not worth it. Unless you can swear by the source of the free software and trust its credentials, don’t be persuaded from the true path. Being cynical and doubting is one of the best features of a sensible surfer.

Adware gets itself installed (often as a trade-off for free goodies), then targets ads at you. But these ads are targeted because if you visit a certain site, lets say on dog leads, then it will send you dog lead adverts.

You can see the logic, but it can get quite tiresome keep getting dog lead adverts, especially when you’ve bought one, and these adware programmes are tracking your surfing habits and can be selling that information to other companies, so that they too can send you ads. Resist the adware temptation; don’t do it, because eventually a dirty piece of code will wheedle its ways into your computer and it won’t be a very enjoyable experience.

Home page hijackers are just that. It’s a programme that resets your home page to its choice, not yours. And when you change your setting back to your own home page, the hijacker changes it back again. And once its done that, it sends you pop-ups and can even re-direct your searches. Hijackers generally don’t have a good press, and these certainly don’t, so be on your guard against them.

Malware is usually infiltrated on your computer as part of downloaded applications, or picked up from a ‘dirty’ website, or on the back of a pop-up.

Now, malware is pretty evil, but the next bunch of villains in the line-up, come pretty close.

Trojan Horses and back door programmes are aptly named. They secretly get into your system and start doing things that you are mostly not aware of until its too late. But they have the same effect as someone sitting at your computer and using it themselves. They enter your system via a software download, or the way that spyware infiltrates systems.

A particular nasty Trojan is what’s known as a keylogger. And, as with most of these things, it’s all in the name. A keylogger records your keystrokes and sends them to the person controlling the trojan. And by logging your keystrokes, they can work out your usernames and passwords etc, effectively then are able to access say your bank accounts with the same information. Not a pleasant thought.

Viruses have the distinction that of being the generic term for all the nasties we’re mentioning here. The true definition of a virus is a piece of software that is invisible and infects your computer by copying themselves onto your applications. And once into your system, it has a number of amusing little tricks for your edification. It might crash your computer, wipe your hard drive, or delete files. Their favourite way of getting in, is within an email attachment.

So that’s it, the basic list of nasties that you might experience as a computer user. But it wouldn’t be right without mentioning, in this section, the delights of spam. Although not technically a piece of code that attacks your computer, spam is one of the scourges of the modern world.

Over 80% of email traffic is spam. It will annoy you, clog up your email box with its futility, occasionally contain nasty viruses and above all, send you into a spasm of frustration as to why people respond to such emails. If people didn’t reply to the offers, or fall for the cons perpetuated in spams, they would eventually disappear, or once again became the playthings of spotty teenagers.

Please, please don’t reply to spams, and nor should you fall for spam emails – known as phishing – which offer you millions in return for say sending an administration fee. It is amazing how many of these emails actually work. It’s as though thousands of us do secretly believe that they do deserve millions left in bank accounts which should come their way for a small administration fee. Okay, lets not go there, but there are so many subtle variations of these attacks, that it’s unfair to point too many fingers. But remember, there’s rarely such a thing as a free lunch.

What’s more subtle, and very effective, no matter how many times you try to inure yourself to it, is the bogus emails from your bank which ask you to send the bank your details if you don’t want to have your bank account closed. Of course, the dead give away, is when you get banks that are not your own emailing you. Then you can smell a rat. But what do the spammers care? They send out so many millions of emails that a high enough proportion will get the right bank and a dozen, or so recipients, might just respond, anxious to not get their account stopped. They send off their details – to a false site of course – and the next thing they know their bank account is closed. Banks do not send such emails. Banks will not ask for your personal details in an email. If you get one of these types of emails, no matter how convincing it is, do not act upon it. If you are convinced it’s genuine, telephone your bank and ask them. If it’s dodgy, most banks ask them to send it to them, as they will have a whole department devoted to fighting spammers. So help when you can.

Oh yes, one final problem. If you run a home network using Wi-Fi, ensure that your signal is protected by a security key. Do not make the mistake of thinking that your hot spot is yours alone. Someone parked outside your house could detect your network on their laptop, so always make sure you’re not letting anyone else in to see what you’re doing.

What Does My PC Need Protection From – Recap

• many nasties out there;
• malicious web scripts and code are bad;
• cookies, often innocent, can track user habits;
• pop-ups, avoid;
• malware, very bad;
• trojans and back door programmes, very bad;
• viruses, bad;
• spam, waste of time for everyone, except crooks;
• Wi-Fi, don’t broadcast your personal details.