Netbooks have exploded onto the market. And apparently it was a surprise to everyone in the computing industry that Joe Public fell in love with them. Oddly, it seemed we weren't interested in investing the monetary equivalent of a luxury Mauritius holiday in buying a steel box of components that connects to the internet and goes beep occasionally.

So in this age with a multiheaded credit-crunching beast roaming the land, netbooks are the perfect low-cost addition to any household. No matter if it's a third system for yourself or the portable that jam-covered little Jimmy has been asking for all of this time.

If you're not familiar with this fast moving new market segment, the technologies and options out there can be bewildering. Don't worry though, whether you are planning to buy a netbook as a cheap Christmas gift for yourself or a friend, we'll be covering all the essentials right here...

Designed for essentials

The original Asus Eee PC 701 was the machine that many consider to have kicked off the whole netbook gold rush. It was designed to provide a low-cost system. And a low price means cutting costs at every stage; a smaller screen, chassis and keyboard coupled with low-power processor and free OS. These all help make an able but frugal system that even Mr Scrooge would be proud of.

But a netbook is not a laptop.

When first considering a netbook it's this frugal design that you need to be aware of. There's a sickly marketing catchphrase that's bound to make you gag as it comes out - which goes: "netbooks are for viewing, not for doing".

This is to say they're great for email, web browsing, 'light' document editing, plus photo, music and SD movie enjoyment. However, the small physical screen and resolution size makes editing photos and complex documents difficult, while anything that requires 3D or CPU muscle is out of the question - so if that puts you off, you might be better off considering a full laptop instead.

Indeed, while £299 seems a perfectly reasonable amount to pay for a netbook, the decreasing prices of full-blown laptops mean that if you want a system for home or use on the move, you may be better off with a bigger and more capable system.

Better battery life

Budget processors always have the tendency to be part of an ageing generation that's been put out to pasture with the larger parts of their faculties lobotomised off.

The original Eee PC ran an Intel Celeron M; based on the classic Pentium-M architecture it offered reasonable processing power even at the very low clock rates the Eee PC uses; a mere 5 Watts.

The newer version is the polar opposite in design terms; freshly built from the ground up. When Intel came up with the Atom platform it had handheld internet devices in mind, so when Asus started dropping them into low-cost sub-laptops and we started buying them, the rest of the world took notice.

It's interesting to compare the performance of the 1.6GHz Atom N270 that lives in many netbooks to the far older 600MHz Celeron M certain models use. Under testing they run about the same speed but key to Atom's design is its ultra-low 2.5 Watt power output. Coupled with advanced sleep states it's perfect for maximising battery life in these cheap devices.

Less common, but used in the HP Mini-Note, is the VIA C7-M range of processors. Similar to the Atom, it's an in-order processor, so lacks a lot of the processing grunt you'd expect from a similarly clocked processor.

Unfortunately, this results in poor speeds even when compared to its velocity-challenged comrades. Just to rub salt into the wound the C7-M can't even really offer particularly amazing power usage, drawing 15 Watts compared to the same-speed 1.6GHz 2.5 Watt Atom.

Pulling the strings

Then, you need an operating system. Netbooks offer variants of Linux, Windows XP and even Windows Vista. Unfortunately, the Vista offerings on the netbook platform have been pretty laughable.

The in-order processors of the VIA and Atom simply can't cope with Microsoft's leviathan OS and things are made worse by the fact that many only ship with at best 1GB of memory. Microsoft may not be happy about it but Windows XP is the only viable option to choose and happily offers perfect performance, which is one of the reasons Microsoft has been forced to extend the supported shelf-life of Windows XP.

Linux is also on offer for many of the netbook models, and if you're either au fait with Linux or are happy to use the supplied apps it makes a perfectly good option. If you're not familiar with Linux and are expecting to install apps, network it with your existing systems or take work home it's probably best avoided - though for simple email and web browsing it makes a good alternative.

Be happy with the screen

If any part of a netbook is going to put you off a purchase, it should be the screen. It was easily the original Eee PC's Achilles heel, measuring less than a manly seven inches with a retro style 800x480 resolution. It was enough to make your poor squinting eyes bleed.

Many more recent netbooks offer far better 1,024x600 screen resolutions. But we'd strongly advise you try one in a shop to see if this is spacious enough for you; or at least try setting your desktop resolution to this as some people simply find it too constrained.

A few more up-to-date models, such as the HP Mini-Note and Dell Mini 12, offer more generous 1,280x800 resolutions, but the price on these are reaching standard laptop levels - missing the point of the netbook in the first place.

Easily save and store

Less of a problem for these tiny systems is oddly enough storage. They may lack DVD drives but as external ones can be used or you can share storage or a drive over a network it's hardly a problem.

Netbooks can be found with hard drives up to 160G; even modest models come with 80GB. The alternative is the more modern solid-state drive (SSD). These may provide a fraction of the storage but help increase battery life, are faster and more robust when it comes to surviving bumps and bangs, which are desirable pluses for a portable device. They are, unfortunately, much more expensive.

Most netbooks support up to 2GB of system memory and will ship with 1GB. It's worth checking if expansion is possible, as the limited size of these netbooks may restrict them to a single available memory slot - usually SD.

Battery life is crucial

If you plan to take your netbook anywhere beyond the butt-cheek depressions of your sofa, then battery life is important. However, lithium-ion batteries are expensive, so in an ultra-cheap device these tend to be the first thing to get cut.

A good tech spec should list the 'mAh' rating of any device's battery. This is the technical measure of a batteries capacity. Cheap batteries (and by that you can read "ones that don't last very long") have capacities around 22,000mAh. These only use two or three cells and you'd be lucky to get two hours continuous use out of them. More expensive models will offer 44,000mAh packs with six cells and double the running time, while high-capacity 66,000+mAh packs are available, often as an optional extra.

What's next?

2009 is going to be the year for netbooks. Real competition from AMD with its Yukon platform and its 'new' Huron processor should keep prices low. While we doubt this will compete directly with Intel's Atom on efficiency or overall power, it should undercut it on price in this already competitively priced area.

Intel also has its new Moorestown platform - superseding the Menlow Atom based devices we currently enjoy. It has even greater power efficiency, will drop to a more efficient 32nm process and is a system-on-chip design. The big advance in netbook design for 2009 will, however, be dual-core processors. Watch this space...

Now read our Netbook Supertest, featuring four very different machines from four different manufacturers.