As science and technology develops fast, a simply mobile phone that could only send short messages and make phone calls is not enough, people are pursuing a mobile phone that can not only communicate with other but as a way of entertainment, so smartphones appear as the outcome. What is the definition of smartphone? http://en.wikipedia.org/wiki/Smartphone explains as follows: A smartphone is a mobile phone that offers more advanced computing ability and connectivity than a contemporary basic feature phone. As plenty of manufacturers who produce smartphones, there are a lot of models for us, what are the factors that we notice when we choose a smartphone?       1.     Appearance. The first thing you may notice is the appearance. Color, contour, bar phone or candybar phone, touch-screen or keypads, or both. You won’t buy an ugly phone, so the manufactures never stop designing their mobile phone with distinctive appearance. But it seems that when one manufacture designs a pretty façade, others would copy it, just another brand, so with similar appearance, what you should do is compare their other aspects.   2.    Brand. Different brands have their own advantages. For example, Nokia is famous for its quality, if your Nokia mobile falls down by carelessness, there hardly has effect on it unless it meets with really a heavy fall. Sony Ericssion has very pretty appearance and iPhone is fashionable. There are five well-known smartphone brands and their main models, they are: Nokia (N97, E72, C5, X6, N95, 6700S…)/BlackBerry (9650, 9630, 8700…)/Motorola (ME600, CILQ, Droid, A1200, V8…)/Apple (iPhone, iPhone3GS, iPhone 4)/HTC (HTC Hero, HTC HD2, HTC Desire…) 3. Battery Life. We are used to the basic use of a mobile phones and their battery power maintaining for a long time, nobody wants to charge batteries frequently; this not only causes troubles in charging but damages the battery. But when we get a smartphone, besides the normal use, we would use it to surf the Internet, play mobile games, connect Wi-Fi or use Bluetooth. These functions may consume your battery fast. Especially the 3G smartphones, they demand high-capacity battery, maybe in the future, external portable power sources will be the standard configuration to solve this problem. 4. Functions. Besides the traditional use of making phone calls and sending SMS (short messages) or MMS (Multimedia Messaging Service), a smartphone also has the following extra functions: GPS, Bluetooth, Multi-media, Wi-Fi, Camera, Network or other functions, as we use more application programs for other applies, compatibility to the applications is very important. Frankly speaking, some of the functions are not useful in our daily life; on the contrary, they may expend the battery power, so my advice is that choose the right one but not the functional one.