With more than 2.3 million members in the UK alone, AOL is one of the world's largest internet service providers (ISP). The company promotes itself as a family-oriented service provider, and was the first to introduce its own web browser software.

So how exactly is AOL different from other ISPs and would its distinctive way of working suit your needs? In this feature, we get inside AOL to find out precisely what it is that sets it apart and whether its particular brand of bells and whistles make it worthy of a monthly subscription fee.

Tight security
Central to AOL's advertising is ease of use and online safety. The company told us that its new set of security tools means that users don't have to buy additional security products.

"Our members can be reassured that, if all the available safety and security tools are activated and used correctly, they shouldn't have to spend money on additional third-party security software," a representative told us.

There are some good tools at work in AOL's package: known email-borne viruses, for example, are tackled before they come anywhere near your PC. Similarly, outgoing mail is checked for bugs, so that you don't inadvertently pass on infectious matter. Your AOL inbox should also be relatively free from spam too, as an intelligent spam filter comes as part and parcel of an AOL account - although more on this later.

Further protection comes in the shape of a free downloadable version of McAfee Personal Firewall Plus for AOL broadband customers, although the same courtesy isn't extended to dial-up users. Invasive pop-up advertising can be blocked too, while AOL Spyware Protection can scour your hard disk for sneaky spyware you might have accidentally picked up, and remove it safely.

This is all very well but we would add that a proper antivirus program is absolutely vital, since infection can occur from sources other than email. Also, users of the company's dial-up service who don't qualify for the free McAfee firewall should install their own firewall too. ZoneAlarm does a fine job, and it's free.

As for spam, AOL's filter does do a good job. A bit too good sometimes. Some users have complained that perfectly valid messages are blocked at the border along with the usual spam ne'er-do-wells and their embarrassing offers. AOL isn't alone in this, as BT Yahoo has faced similar accusations, but any technical effort to block spam is a balancing act.

Spam may be easy to spot in your inbox, but when a company is processing millions of emails every day the process has to be automated. That means you have to set a definition of a spam email, and that's where the problems arise as any genuine email - such as a newsletter you have actually subscribed to - may bear the hallmarks of 'unwanted' offers.

AOL's new Safety and Security Centre is where you'll come across the rather handy Computer Check-Up tool. This utility takes a snapshot of your PC, pinpointing possible problem areas - anything from low hard disk space to web cache settings - and suggests fixes for them. In some cases, Computer Check-Up will even be able to automatically repair minor faults for you.

Safe to surf
Another of the company's key claims in protecting your PC from net nasties is that it only allows you to access the internet using AOL's own software. Once connected, you can launch your preferred web browser but you need to keep the AOL software running in the background.

It's based on Microsoft's Internet Explorer, which raises another issue - AOL's browser is prey to the same security vulnerabilities as Microsoft's product, so the AOL experience will be safe only if users remember to turn on automatic updates or manually download them from Windows Update. AOL does provide a tool that reminds users to do so, but it seems a controversial choice of browser for a safety-conscious company.

All of Internet Explorer's familiar toolbars are absent from the AOL browser window and navigation is performed using floating AOL toolbars. If you're used to seeing a standard browser this can be a bit disorientating at first. We found that it was easier to maximise our browser window, which has the effect of reintegrating navigation controls back into the browser itself.

Keywords can be used to get directly to certain web pages without having to type in long website addresses. This can be handy, but tends to be used mainly for navigating AOL's own services and help pages, as the system hasn't been widely adopted outside of the company itself.

Advanced web users may find the AOL experience just too cosseting for their tastes. And, in its attempt to hold the hand of the uninitiated user, AOL occasionally manages to over-complicate things. The tabbed layout of the email client, for example, doesn't feel particularly logical and would benefit greatly from a simplified interface.

Also, you can't use any existing POP3 email accounts you might have within AOL, so you'll need a separate email program or webmail client if you want send and receive messages through anything other than your @aol.com address.

Media matters
Those who like to customise their browsing experience with add-ons and plug-ins might find AOL's proprietary system a little frustrating, as it is intended to work without the need for any additional software. The AOL Media Player, for instance, is designed to handle all video and audio duties, but, in reality, you'll still need Apple's QuickTime installed if you want to view content in that format.

We also found that the AOL player occasionally drew a blank. Attempting to listen to the RealPlayer snippets of songs on Amazon, for example, resulted in a "this file is not supported" error message. Java and Shockwave, on the other hand, integrate into AOL seamlessly.

What this means is that you'll have to download these plug-ins and install them yourself, although only if you find a piece of media you can't play back in AOL.

It is also possible to run an alternative browser, such as standard Internet Explorer or Firefox, alongside AOL, if you wish. Less encouraging results were experienced when we attempted to install the Google toolbar.

This failed to appear anywhere in our browser window, even after an apparently successful set-up. Admittedly, AOL already includes a Google-powered search box on its Welcome screen as well as a Google Search button on the main toolbar. But if you want to use your own choice of browser, you'll have to access Google by visiting its main website.

Child proofing
Paramount among AOL's concerns is that its service is safe to use for families with children. Consequently, along with the security features we've already mentioned, AOL allows parents to configure their systems to prevent unsuitable web content and features from being accessed by their kids.

This works by assigning each member of the family their own account (or Screen Name in AOL-speak) and allowing each person their own set of privileges. AOL makes this easy by listing various age categories (Kids Only or Young Teen, for example), all of which are fully editable.

If you have very young children, for instance, then setting their access privileges to Kids Only will mean that your kids will be able to only browse certain pre-approved websites and unable to use an instant messenger.

Should you ever become concerned about the amount of time your kids are spending online, you can limit their access to a couple of hours a day and even dictate what times of day they are allowed to use the internet.

Parents who aren't able to physically monitor what their offspring get up to while they're online can use AOL Guardian to keep a record of sites visited and chat room activity to make sure there's nothing untoward occurring.

If a child wants access to a restricted website, they can use AOL Guardian to make a 'formal' request, which will be emailed to the parent for approval. Similarly, any usage monitoring that you do is always carried out with the child's full knowledge, neatly avoiding the negative implications of spying on your own child.

That may sound a little strict, but at least AOL seems to be attempting to use the parental controls to open up a dialogue between adult and child about the internet, which can only be healthy.

That's entertainment
When you install AOL from a CD-ROM, you're not just adding a few shortcut icons to your Desktop. AOL is a fully featured program - currently on version 9 - that has been built around a custom web browser, an email program and media player with built-in security and messaging tools.

A lot of ISPs provide a portal or home page where subscribers can find the latest headline stories and a few interesting titbits to browse through every time you log on. AOL, though, takes this part of the service pretty seriously.

Referring to itself as an 'online service provider' rather than a plain, old ISP, AOL considers its online content to be a big priority. AOL is part of the Time Warner empire and holds the rights to many movies and recording artists.

On the music channel, for example, you'll find streamable pop videos of the latest chart hits as well as Sessions@AOL - live performances and interviews with artists recorded exclusively for AOL members.

Also, AOL has just signed an agreement with Sky Sports to provide AOL Gold and Platinum members with extensive downloadable video content, including highlights of the Premiership and the Champions League football, rugby, cricket and boxing.

Even more news, gossip and useful information can be found by clicking on one of the 24 Quick Links listed on the Welcome screen - these are sorted into categories such as Careers and Jobs, Kids, Learning, Money, Shopping, Teens and Women. Each mini-site has a decent amount of up-to-date content as well as links to relevant external services, such as eBay.

The one criticism we might have here, however, would be the high level of aggressively targeted advertising. Click on the Careers Quick Link, for example, and you could come face to face with a big banner ad for Monster. And, while AOL includes a pop-up ad blocker, this obviously doesn't seem to work on the service's own advertisement windows, which will occasionally appear when you log on to the service.

More fun than we can handle
There are other features built into AOL that we haven't got the space to look at in detail. You can, for example, create an online photo gallery and build your own website, although these features are hardly unique. Using its Instant Messenger software, users can chat or have video conferences with friends, although you don't need to subscribe to AOL to benefit from this.

Is AOL for you?
It's true that AOL's features differ from other services, but we're not entirely convinced by the idea that it is a different type of provider altogether. The service has proved popular with those who want to share the internet with younger family members, and we salute the company's approach to encouraging discussion about the limits placed on children's online time.

With video-on-demand services reportedly in development, AOL would seem to be capitalising on its reputation, as well as its entertainment industry roots, in order to bring yet further unique features to its members.

It is not alone in this and with BT Yahoo now offering its own browser, it seems that mainstream ISP services may be making another subtle shift back to becoming content providers, rather than just granting access to the web.

Whether you like the kind of content on offer is likely to be the key factor in your decision of which ISP to choose. Another important consideration in this market will be customer service and AOL provides 24-hour telephone support completely free of charge, which will appeal to those less confident with the technicalities of the web.

Parental control without AOL
One of AOL's best features is its parental controls. But if you're not an AOL member, you don't have to switch to the ISP just to help keep your kids safe from unsuitable online material. Instead you could opt for one of the many content-filtering tools that are available.

Programs such as Net Nanny and CyberPatrol provide lists of websites that are automatically blocked. These lists are regularly updated in order to make sure your kids are constantly protected.

Alternatively, you could try using a browser that has been designed specifically for children. These work just like Internet Explorer but restrict your kids' browsing just to 'safe' sites with content that is suitable for kids.

There are a handful of free kids' browsers still around, such as Kid Rocket, but remember that, with any of these products, there's no substitute for supervising your child's internet access in person.