The internet isn't compared to a highway for nothing - and like any road, you want to take care when you're travelling on it. A few precautions can make your web experience a lot safer.

1. Look for the lock

Many websites ask you to pay for products and services online. But it's fairly easy to intercept web communications, so how do you know that while you're buying your copy of Crime and Punishment from a bookstore that someone isn't copying down your debit card details in order to empty your account?

Reputable websites will scramble your information as it gets sent across the wires - but how can you tell if they're doing this? The easiest way to set your mind at rest is to have a look at the address bar of your browser - the bit at the top. If the address starts https:// instead of http://, that's a good sign - the "s" shows that you're on a secure site.

Other signs are small padlock icons in the address bar, or at the bottom of the screen; or, if you're using Firefox, the address bar turning yellow. You can also set up your software to alert you when you leave a secure website - a handy reminder to be on your guard.

A mother and child online Copyrighted image Credit: Jupiter Images

2. Treat your personal information with care

There's a lot in the media about people being tricked into handing over private data to criminals online, but it's possible to avoid being duped if you keep your wits about you. Keep an eye open for phishing - when you get an email apparently from your bank or other financial institution asking you to "update" or "verify" your log-in details, complete with a link which takes you to a plausible-looking website.

You type in your account and password details, and before you know it, your account is being emptied and your hard-earned money is being spent on beer and jewels by conmen. No bank will ever send you an email that asks you to do this; never provide password details when asked to by a website which opens when you click an email link.

Phishers are, effectively, blindfolding you, driving you through the streets and then removing the blindfold in a room which has been designed to look quite a lot like your bank's branch, but where all the "staff" are just people trying to trick you into handing over your valuables. The way to be sure you're really where you think you are is to drive yourself to the front door - or, online, by typing the web address (e.g http://www.mybank.co.uk) directly into your browser.

And be careful when you reveal details about yourself online. It might seem a good idea to say "I am going to Botswana for the next fortnight" on your blog. However, if you've already told readers you live in Clinton Ferrers, you blog under your real name and you're in the phonebook, you might as well hang a big sign saying "House Empty" on your front door.

3. Protect yourself against viruses and hackers

If you were off to Botswana, you'd check if you needed to see your doctor for inoculation against any diseases common in the region. Likewise, before going online, it's good to make sure you're protected against things you might pick up off the internet.

Viruses are small computer programs which sneak onto your computer and do things you might even not know about. Some are dedicated to just replicating themselves, copying their code across to everyone in your address book. Some are nasty, and will delete chunks of your data. Others will watch what you're doing, hoping to find out personal details to send back to their creators. Still others will turn your computer, unwittingly, into a spam-sending machine. About the only thing computer viruses won't do is make you sneeze. Not yet, anyway.

It's good to try and avoid computer viruses in the first place - by not opening emails from people you don't know, and never, ever opening attachments you're not expecting.

But even the most careful person can sometimes stumble across a virus - they can be hidden in pictures on the internet, for example. So it's vital to install anti-virus software on your computer, and ensure it's kept up to date. Good software will check every file as it appears on your computer, and alert you if there's something strange going on.

You can also protect yourself from more direct attacks on your computer - hacking, where someone uses your web connection as a way in - by ensuring that your have a firewall installed and switched on. Most recent operating systems have a built-in firewall; double check that it's activated and ensuring that only the people you want to access your PC are getting in.

Some anti-virus and firewall software is available for free. See five ways to use free software for more information.

4. Keep your software current

There are enough people who are keen enough to break into your computer that they work constantly to find new ways in. Software manufacturers toil, equally tirelessly, to try and stop them.

The process is a little like having zombies trying to break into your house: they'll gather round the door until you push the sofa in front of it, then they'll start trying the windows. Microsoft, Apple and the others are constantly boarding up each window as the zombies discover it.

Check that you're helping by setting your computer to check their websites regularly for the latest updates. If you have a Windows PC, you can get an online scan to see that you've got things covered.

5. Protect your machine, protect your data

The stuff you've got on your computer is important to you - emails from your admirers, photos of your lovers, a video of you playing air guitar. If something happened to it, it's irreplaceable. And things could happen - what if a virus wiped your hard drive? Or your PC got stolen? Or you knocked a glass of beer into the machine while reprising your air guitar performance?

Luckily, the stuff on your PC is replaceable, if you copy it. The process of duplicating your valuable files is known as "backing up", and in the versions of the Mac and Windows operating systems coming later this year, it's going to be as simple as pushing a single button. But even if you don't have them, backing up can be easy - burn a CD or DVD with your files on it and keep it somewhere safe, and do this regularly.

Or choose a secure service that allows you to store your files online - some even offer a program which will do regular back-ups for you. (The Wall Street Journal has more about some of the services available). Another option is a small USB drive which plugs into your computer, or, for more files, an external hard-drive. To be really sure, you should use more than one method.

Toughen up

Learn more about the threats, and how to protect yourself, with the Open University's course: Vandalism in Cyberspace:Understanding and Combating Malicious Software.

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