It's very simple to check if you have a wireless card installed in your computer.
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Windows: Go to Start > Control panel > Network and Internet > Network and Sharing Center. If there is a menu on the left called Change Wireless adapters, click it. IF you see a network adapter installed, then you have wireless card.
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Mac: Click the wireless sign in the Finder bar, then go to Properties. On the left section, you should see all the devices. If you have a wireless card, it should displayed as a network adapter.
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Linux: Start terminal then type: sudo ifconfig and type your password. If you see wlan0 then you have a wireless card attached.
