Every PC and laptop needs antivirus, antispyware and a firewall. But what constitutes 'good' security software? Here we outline what to look for when selecting your desktop or laptop's defensive arsenal.

If you have a Windows PC, especially one connected to the internet, you must run reputable security software. There's no excuse: even if you have no concern for your own computer and data, leaving a system unprotected encourages cybercriminals, and makes the computing world worse for us all.

It's also important that your internet security arsenal is kept up to date. And although some users may prefer to mix and match products to produce their perfect blend, it often makes sense to install an internet security suite that contains all the necessary elements.

The best products will offer features that go beyond the traditional antivirus, antispyware, antispam and firewall concoction of internet security suites – you might see parental controls, 'cloud' protection, anti-phishing, anti-rootkit, virtual web browsers and keyboards, link- and file scanners, gaming modes, online backup and more included. As malware develops more quickly than ever before, signature-based virus detection is no longer enough, and we suggest that any package worth its salt should have at least behavioural protection. See also: Group test: what's the best security software?

Installing multiple security products from different vendors is usually a bad idea, as they can conflict. With many households now owning more than one computer, the best value is usually offered by a one-year, three-user licence. However, you can save some cash with a single-user licence if you have only one computer.

If you're happy with your product and prepared to take a punt on its future performance, you could save money by signing up for two or even five years.

Not all security products are created equal, however. To help you decide which of each type of product to install, we work with world-renowned independent security testing lab AV-Test.org to evaluate the effectiveness of security software. No security software is foolproof, but be sure to check independent test results such as our Top 5 chart to make sure that your chosen product is of the required standard.

Here are 12 key things to look for when assessing which software to choose. Not every program or suite will have all these features, and that's fine. Consider these features signs of a good setup, and try to blend together as many as possible. We've assigned each a level of importance to further help your decision.

Security software: The basics

1. Signature detection. Once upon a time, signature-based detection was the be all and end all of security software. This is the method by which malware in the wild is recognised and analysed by security experts. They then upload the signatures of viruses and their dodgy brethren, telling your PC not to allow such filth to install.

The advent of 'zero-day threats' – vulnerabilities exploited on the day they are discovered – has marginalised signature-based antivirus and –spyware. The creation of malware has been commoditised to the extent that anyone with a bit of cash and tech savvy can become a hacker: analysis simply can't work fast enough to keep up.

But we're a long way from a world in which signature-based antivirus is not required. With literally millions of pieces of malware in the Windows world, a solid virus database gives your PC a base level of protection, removing the vast majority of threats from the equation before the more labour-intensive security functions take over.

Importance: 5/5

2. Behaviour- and cloud-based detection. These are the functions that take over when the signature database has done its thing, and both are rapidly becoming crucial to any security setup. Security vendors often append fancy names to these functions; ultimately, you're looking for features that can discern new and unknown viruses by monitoring processes' behaviour, or judge software on the basis of user experience.

Behavioural or heuristic detection judges potential malware based on what it does to your PC. But legitimate software may require access permissions very similar to those requested by malware. False positives can be a problem, so it's important to check independent reviews.

The best security software supplements behavioural detection by taking note of the choices users make when presented with a malware warning. Intelligent software can then assign a user-led rating to suspect programs, adding weight to the suspicions of the behavioural engine, reducing false positives and speeding up the whole process.

The bigger the userbase, the better the quality of its crowd-sourced information – but this doesn't mean only the biggest players are worth consideration, since vendors often share user information. Independent reviews can help you judge their effectiveness.

Importance: 5/5

3. A robust, two-way firewall. Windows has its own perfectly acceptable firewall, and any security suite you buy will come with its own software that filters out threats before they get anywhere near your system. But not all firewalls are created equal.

The best firewalls have additional functions that, for instance, monitor your internet connection and keep strangers from accessing your Wi-Fi. They should also be just as vigorous at preventing data leaking out from your PC as stopping your system pulling down malware. You also need to make sure your chosen firewall is regularly updated. And if you are using a third-party firewall, ensure that you disable the native Windows one.

Importance: 5/5

Security software: Recovering from disaster

4. Cleanup or rescue mode. It's critical that your chosen security software is as good at removing threats as it is in finding them. But discerning how successful each program is at this crucial function can be difficult to judge. As we may have said before, independent reviews from magazines such as PC Advisor are your friend, in this regard, but there are some features to look for that will help you make a decision.

Any security software that's serious about malware removal should have some kind of cleanup or rescue mode. This should be a function that can start your PC in a trusted environment, which is then used for cleanup and restoration with no danger to your data. It's by no means critical, but a useful addition.

Importance: 2/5

5. Data protection, theft prevention and privacy. All malware exists for one reason: to make money. The best way of doing that is to steal your data, then spoof your persona to make purchases, sell your details to spammers, or simply dip into your bank account. As an increasing amount of our connected computing happens on laptops, tablets and smartphones, modern security software has to protect you the person, rather than just your devices.

If your laptop is stolen and it's insured, you can replace the hardware. The loss of the data held on it may be less easy to recover. And that's before you consider the sentimental and monetary cost of having to replace personal photos and purchased movies and music.

The ideal security setup should include some form of data filter that prevents critical information such as your bank details from ever leaving your computer, except for legitimate reasons. Anti-phishing, the ability to block websites supporting scams or credit-card phishing attempts, is critical here, as is encryption of email, IM and file transfer.
And the best security software offers functionality that will allow you to recover quickly from a potentially critical theft: virtual or physical. The ability to remotely locate, message and wipe your lost laptop or smartphone is key.

Importance: 4/5

6. Secure backup. Backup is a hassle, until it's required; at which point it becomes your best friend. While not strictly a security feature, the best security software offers secure online space to protect your critical files. Look for storage options where data is encrypted using industry-standard AES algorithms, ensuring that it's never accessible to malicious third parties.

Importance: 5/5

NEXT PAGE: protecting you from you >>

You have PC or laptop and you have faithfully installed antivirus, antispyware and a firewall. What other security software should you install, and do you know what you have is any good? Here we continue our guide to what to look for when choosing security software.

Security software: Protecting you from you

7. Antispam, phishing and email protection. Spam isn't just annoying, it's potentially very expensive indeed. And the havoc it spreads is exponential, potentially affecting everyone in your inbox. The weakest part of any security setup is you. It doesn't matter how carefully you build your PC protection from the outside, nothing will keep you safe if you invite cybercriminals on to your PC via email.

Email spam can take many forms, from adverts for dodgy pills and services, through phishing expeditions and poisoned links, to messages that masquerade as helpful tips or jokes, but are principally a means of spreading malware. And the people who spread such filth are getting more clever every day, creating seemingly plausible messages that are able to hoodwink even the most wary user. It's reaching the stage where anyone can be fooled, so some form of email protection is critical. Look for the ability to check links and files in emails, and a robust antispam function.

Importance: 4/5

8. Parental control, usage rules. Other functions that, like email protection, save you from yourself. Good parental controls will block inappropriate content, restrict web access between certain hours, and help parents remotely monitor their children's online activity. More importantly, it should be simple to do so, and difficult for your more tech-savvy kids to hack in and reverse the rules. It's also worth looking for usage rules on a broader level: the best security software will allow you to set rules that can be disobeyed only by an administrator.

Importance: 3/5

9. Social networking protection. Ask PC users in most households what they use their computer for, and the answer will usually include the words 'iPlayer' and 'Facebook'. All modern security software should provide social-media protection.

The best security software protects you and your friends from e-threats that attempt to exploit the trust you've built with them over social networks. After all, you never really know who's on the other side of an online relationship. Such software works by filtering the links you receive from your Facebook and Twitter friends, and monitoring your privacy settings to ensure that you aren't giving away too much in the rush to be social.

Importance: 4/5

10. Safer search and surfing. Because you don't always want to use a virtualised browser, it's worth looking for general protection when you're out and about on the open internet. Good security software gives advance warning of risky websites in your search results. Tools such as McAfee SiteAdvisor and Web Of Trust also block sites as you click dodgy links, and send warnings of potentially dangerous territory as you download a web page. The very best security suites will include such functionality as standard.

As this information tends to be sourced from users, and web surfing is a very personal thing, false positives can be a problem. It's critical that any safer-surfing software is customisable. In essence, you want to be able to set the level of security you need, and adjust it to make exceptions.

Importance: 2/5

Security software: Nice, not critical

11. Sandboxing, and a virtualised browser. A nice, if not crucial, function is the ability to test the waters of potentially dodgy software in a secure environment. A virtual browser isolates your web-surfing experience from the operating system, allowing you to block web-based threats as you surf to potentially dangerous waters. A sandboxing environment is a similar function, but for full-blown software programs.

Importance: 3/5

12. PC maintenance functionality. Just as ticking off known virus signatures is no longer enough, simply focusing on keeping bad things off your computer is only the start of making sure everything is ship-shape. PC maintenance software is a class all of its own, and you certainly shouldn't base your security decisions on the disk-optimisation tools bundled with a suite. But the best software will take a look at your computer's performance as a means of diagnosing an otherwise undetected infestation. It's also good to have a utility that checks for missing security software, or outdated programs, as well as potentially unsafe system settings.

Importance: 2/5