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Which computer you choose will depend on what you want to do with it. If you need to spend a lot of time at your computer, or you like to play the latest games, then you really need a large computer under your desk and a monitor (or two) on the desk along with a mouse and a good keyboard. The advantage of these 'desktop' or 'tower' computers is that you can change components such as the memory or graphics card relatively easily. The disadvantage is that is hard to move them, and they run out of power very quickly unless they have a mains electricity supply.

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After smartphones, tablets are weakest in power and performance. However, tablets can run all day, and are suitable for emails, and watching multimedia. Many tablets come with bluetooth keyboards, so you can even do a lot of typing on them. You can carry them in a handbag or in a briefcase, so they can stay with you all day, and they have another advantage - they can turn on and off instantly. The smaller screens and low power mean that tablets can never fully replace a desktop computer. However, they are all that some users need.

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A smartphone is actually a small computer that can do more than some desktop computers could do a few years ago. Smartphones can screen television and video from the internet, and can be used for communication through social media and text messages. They have address books, can take pictures and video and can be used to read e-books. Oh, and you can use them as telephones as well.

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A laptop is a compromise. It tries to be as powerful as a desktop, and as light and portable as tablet but it ends up as something in between. Modern laptops can do almost anything a desktop computer can do, though the smaller and lighter the laptop the less powerful it is likely to be. Also the screen and the keyboard are less suitable for extensive use. Another disadvantage of a laptop is that the parts are not easily replaceable. However, a laptop can be carried in a briefcase or backpack, and a desktop computer can't be.