Many of this year's hottest new laptops are about one word: Ultrabooks.
The term Ultrabook is actually pure marketing, dreamt up by Intel for a new generation of portable PCs featuring its technology.
Like Centrino but unlike Viiv, it's starting to stick as a catch-all term for thin and light laptops, or ultraportables as they're sometimes classified.
The best way to think of an Ultrabook is a MacBook Air that isn't made by Apple, a netbook that isn't underpowered or a laptop that's been on a crash diet. Ultrabooks all feature a Core i3, i5 or i7 processor, plus fast SSD storage and USB 3.0 connectivity.
Check out our video guide to the Ultrabooks that are set to hit the shelves during 2012.

According to Intel, Ultrabooks also have "ultra-capabilities" - security features, battery power, instant-on and quick standby. They'll provide a lightweight alternative to tablet devices for people who just can't work without a full QWERTY keyboard.
Intel has announced a massive $300m (£185m) fund to help develop Ultrabook hardware and software, and it's confident that Ultrabooks will make up 40% of the market by 2012.
The first models are shipping with current generation Sandy Bridge Core processors, which will be replaced this year by a new generation of Ivy Bridge chips.
Intel set an initial price target of $999/£999 for Ultrabooks, though many have been more expensive - expect serious in-roads on the cheaper £600-£800 market this year.
But what's the best Ultrabook to buy? Check out the best Ultrabooks we've reviewed, as well as some we got hands on with at CES 2012.

1. LG Z330 and Z430 Super Ultrabooks

LG z330

Rather than a tapered design, the chassis on the 13.3-inch LG Z330 Super Ultrabook is 14.7mm thick from front to back. It runs Windows 7 (for now) and has a bigger brother, the LG Z430, which comes with a 14-inch display. Why is it 'Super'? Because LG says so.

2. Asus Zenbook UX31

Asus zenbook ux31

Asus has done a terrific job with the Zenbook's design - even if you have to acknowledge that the designer took more than a sneaky glance at Apple's ultraportable first.The 13-inch Zenbook is fantastic to look at. When closed, the wedge-shaped laptop measures 17mm at its thickest point and a mere 3mm at its thinnest.The same design thinking even stretches to the Intel Core and Windows 7 stickers. We wonder who it was that proposed they were silver and black - Intel? Asus? - but whoever did has made a difference.

3. Samsung Series 5 Ultra

Samsung series 5

Packing an Intel Core i5 processor, the Samsung Series 5 Ultra is small but perfectly formed. Available in 14-inch or 13-inch models, the 13 incher is 17.6mm at its fattest point, narrowing to 14mm.
It comes with a 128GB/256GB SSD or a 500GB hard drive (alongside a small 16GB flash drive) and incorporates an LED SuperBright screen. The only worry? Battery life is low at around three hours in our tests. Not to be confused with the Samsung Series 5 Chromebook. Which is definitely not an Ultrabook.

4. Samsung Series 9

The samsung series 9 ultrabook on show at ces 2012

While the original Series 9 was one of the world's thinnest laptops, the newSamsung 9 Series Ultrabook is even thinner.
The design team has shaved off another 4mm, giving this 13-inch (1600 x 1200) laptop a waistline of only 12.9mm. Inside, a 1.7GHz Core i7 chip does all the hard work, ably assisted by up to 8GB of memory and SSD storage.

5. HP Folio 13

The hp folio 13 ultrabook on show at ces 2012

As the moniker suggests, the HP Folio 13 is yet another 13-inch Ultrabook. It's not much of a looker and, at 18mm around the middle, it's not the slimmest Ultrabook at CES.
But HP is claiming a 9-hour battery life for the Folio 13, which will be ideal for regular mobile workers who value staying power over pretty design.

6. Lenovo IdeaPad U300S

Lenovo ideapad u300s review

Lenovo hasn't obsessed over aesthetics, and this laptop is no Apple MacBook Air clone. It seems chunky next to the wafer-thin Asus Zenbook, which features a wedge-shaped design that tapers off to a thin, blade-like point.
The Lenovo IdeaPad U300S retains its 16mm thickness across the chassis, giving it the impression of being squat. The body is aluminium, and weighs 1.4kg, the same as the Acer Aspire S3, but much heavier than theToshiba Portege Z830 and the Toshiba Satellite Z830-10U. If you're looking for an ultrabook that will turn heads, you will most likely look elsewhere, but can the Lenovo IdeaPad U300S impress with power?

7. HP Envy 14 Spectre

The hp envy 14 spectre ultrabook on show at ces 2012

The HP Envy 14 Spectre is a little bigger than your average Ultrabook and a little fatter because of it. Intel specifies a sub- 18mm chassis for 13-inch models, but 14-inchers like this can bulk up to 21mm.
With a Core i5 (or i7) processor and 128GB HDD inside, HP claims a 9 hour battery life for the Spectre. And... that's really the only appeal.

8. Dell XPS 13

The dell xps 13 ultrabook on show at ces 2012

The Dell XPS 13 might be a little late to the Ultrabook party, but it's one of the prettiest portables we've seen.
Amazingly, Dell has squeezed an Intel Core i5 or i7 inside the trim chassis, along with 4GB of memory and a 128/256GB SSD. How thin is it? 6mm at its slimmest point.

9. Asus Zenbook UX21

Asus zenbook ux21

The Asus Zenbook UX21 is the first 11-inch ultrabook to hit the shelves. Of course, comparisons will be immediately drawn with the Apple MacBook Air, which is one of the best ultra-portable laptops money can buy, and these two 11-inch portables are very closely matched. The Asus Zenbook UX21 matches the Apple MacBook Air in every respect. It's just as well-built, made out of a single piece of aluminium, just as light and oozes the same head-turning style and class that makes people cast admiring glances while you work in public. It also has the same Intel Core i5 low voltage 1.6GHz processor, and a 128GB solid state hard drive, which keeps the system really responsive and fast.

10. Lenovo IdeaPad U310 and U410

The lenovo ideapad u310 ultrabook on show at ces 2012

The Lenovo IdeaPad U310 has a distinctly MacBook Pro vibe to it but these Ultrabooks are expected to be at the cheaper end of the scale, around £600 or so. Packing a 13-inch display, the U310 tips the scales at 1.7kg and is squeezed into an aluminium chassis that's 18mm thick.
A Core i5 chip is expected to provide the processing grunt, with the choice of a 64GB SSD or 500GB hard disk for storage. There's also a U410, boasting a 14-inch display.

11. Toshiba Satellite Z830

Toshiba ultrabook

The Toshiba Satellite Z830-10U, priced at £999 in the UK (the US price isn't yet available).
At its thickest point, the Satellite Z830-10U measures only 16mm across, but Toshiba has still packed in Sandy Bridge power and given us one of the best trackpads we've yet seen on an ultrabook. It's not without niggles, however, and we found parts of the chassis to be inferior to stronger machines such as the Asus Zenbook.
It's the lightest Ultrabook chassis we've yet seen, but also an excellent battery life, this could be the answer for frequent travellers who need a long-lasting machine full of performance for under £1,000.

12. Lenovo IdeaPad Yoga

The enticing lenovo ideapad yoga ultrabook on show at ces 2012

We're loving the Lenovo IdeaPad Yoga. This flexible, foldable Ultrabook also converts into a 16.9mm thick tablet with a 13.1-inch (1600x900 pixel) touchscreen.
Running Windows 8 you get the best of all worlds - a QWERTY keyboard for heavy duty working and a tablet experience for after hours net sessions on the sofa. The downside? It probably won't be cheap.

13 Acer Aspire S3

http://cdn.mos.techradar.com//Review%20images/TechRadar/Computing/Acer%20Aspire%20S3/Acer-S3-Ultrabook-Open-218-85.jpg

The 13.3-inch Acer Aspire S3-951 is an appealing prospect for regular travellers. The Intel Core i7 2637M version we tested is priced at £900 in the UK and costs $1300 in the US (where it has the more specific name of Acer Aspire S3-951-6432), which is enticing, considering the impressive specs list.
A less powerful Core i5 model can be bought for £700 in the UK, while in the US there are three cheaper Core i5 machines, two of which cost $900, while one retails at $1199.

14. The Intel Nikiski concept

The intriguing intel nikiski concept laptop has a dual purpose glass touch panel

While not technically an Ultrabook, Intel tells us that a Ultrabook version of the oddball Nikiski is on the cards for later this year.
What makes it stand out is the glass touch pad that turns into a touchscreen layer to enable you to browse a slimline view of key information such as new emails.

15. Acer Aspire S5

The acer aspire s5 ultrabook on show at ces 2012

Thin (15mm) and light (1.35kg), the new Acer Aspire S5 isn't much of a design departure from the older Acer Aspire S3.
But it takes advantage of its Ultrabook DNA with a 13.3-inch display, Thunderbolt technology, SSD storage and a fast (but as yet unspecified) Intel CPU. Are we excited? Meh.

16. Novatech nFinity 2367 Plus review

Novatech Nfinity

The Novatech nFinity 2367 Plus is the first Ultrabook we've seen that isn't from an established, global computer company. That isn't to say Novatech is small. The British firm has been selling both components and customised PCs for a while, and in keeping with tradition, there's plenty of choice with its Ultrabook range, with the option of an Intel Core i3, i5 or i7 processor, and varying quantities of storage and memory. The Core i3 Novatech nFinity 2367 Plus model that we were sent is priced at just £625, and comes with 4GB of memory, a 128GB SSD and Windows 7.