An air card is a device you can use to connect to the internet with. Air cards for laptops can be purchased as a PCMCIA or USB device and are usually used in conjunction with a SIM card. It is then possible to connect to a WISP (wireless internet service provider) in order to surf the internet. Mobile devices popularized 3G technology, and since then it has migrated onto the computer scene in order to provide a means of wireless internet that is available almost anywhere. Air cards are commonly referred to as 3G cards. They are developed by Sierra Mobile and will allow us to establish a connection to the internet from any location within the coverage zone of your WISP. In most companies your cellular network will provide a WISP service. Some networks offer a free air card when you take out a contract with them. Certain WISP's do not make use of the 3G signal range, but rather use their own signal distribution network. You will need different hardware when connecting to these ...