They are small, light and cheap and intended for the internet, not for running games and large applications. Mini-notebooks, more commonly known as 'netbooks', were originally designed and marketed as secondary personal computers. Today, they are the best-selling PCs on the market. At last month's International Consumer Electronics Show in the United States, the world's biggest consumer electronics trade show and exhibition, netbooks took centre stage as most of the major PC makers showcased new products and prototypes. According to electronics retailer Fortress and netbook software supplier Microsoft, the most in-demand models include Acer's Aspire One AOA150, the Eee 1000H from netbook trailblazer Asustek Computer, Lenovo Group's S10, Hewlett-Packard's Mini 1001TU, the Inspiron Mini 9 from Dell and Samsung Electronics' NC10. Their compact size, helped by a display that can range from 7 inches to about 10 inches, means you can take netbooks, which cost from HK$3,000 to HK$5,000, almost anywhere - the smallest models fit inside a briefcase or handbag. They are light and reasonably robust; most netbooks come with the latest solid-state drives for storage, in lieu of hard-disk-drive technology, to make them capable of withstanding the odd knock. Like regular laptops, netbooks have pre-installed operating systems and built-in cameras, memory-card readers and Wi-fi support. Some models even have 3G modems. Netbooks need relatively less power and some deliver up to eight hours of battery life. Mini-notebooks have their drawbacks, of course. They are not intended for anything other than surfing the internet and a small screen used over a significant period of time can strain the eyes. As there is no built-in optical drive, users must attach an external drive to access a disc. Before buying a netbook, you may want to ask yourself the following: Regular laptop or netbook? The power of a full-featured PC - with its high-performance processor and operating system, graphics chipset, big screen and full-size keyboard - is better for tasks such as editing a video and preparing office documents. The battery life and low-power processor of a netbook are great when you simply want to watch clips or streaming video from the Net, for example, but will not be enough to run demanding business programs and multitasking applications. 'The plastic casing of a typical netbook is also thin and its joints can be delicate,' says Ken Ng Chung-hee, merchandise director at Fortress. 'It is alright to use a netbook in a coffee shop or at a mall but if you need a computer for regular use at a construction site, a netbook would probably not be suitable.' Is the processor type important? Nearly all netbooks use Intel's Atom processor. It is an efficient chip - about as powerful as the old Pentium III. It may not sound like much in these days of dual and quad-core processors but a few modern tweaks help the Atom keep up. It draws just 2.5 watts, so is relatively untaxing on the battery. Intel rival Advanced Micro Devices has recently announced its own low-wattage processor, the Athlon Neo, designed for the netbook and other ultra-portable computers. Is there enough storage? Some netbooks have 120GB or more of hard-disk storage. But the problems with traditional hard disks - based on spinning magnetic platters - are the noise and heat they generate and the amount of power they require. Hard drives are cheap to manufacture, so you can get a lot of space for your money, but they break easily. Most netbooks come with smaller, sturdier solid-state drives, which use flash memory. They are more expensive, so an SSD-based netbook might have a smaller amount of on-board storage than hard disk drive-based models. The advantages are that they are less draining on the battery, shock-resistant and relatively quiet. What connections does it have? All netbooks have Wi-fi support and wired network ports but it is worth looking at models that have faster 802.11n and wired gigabit networking connections. Bluetooth, a wireless protocol for exchanging data over short distances, allows you to hook up a 3G mobile phone and use it as a modem - if your netbook does not have embedded 3G support - to stay online wherever there is network coverage. How long will the battery last? Getting a netbook with good battery life is imperative. Battery packs are measured in milliampere-hours (mAh). Standard batteries are about 2,200mAh, enough for two hours' use. It's worth spending more for a netbook with 6,600mAh or greater. Acer's Aspire One, for example, has a nine-cell 7,800mAh battery.