Wireless USB card is a wireless network card, which plugs into the USB port of your computer and allows you to connect to a wireless network (Wi-Fi or carrier's cellular network). If several years ago people used wired Internet connection mostly, then recently many people use wireless Internet. There are many free Wi-Fi spots in cafes, hotels, restaurants, public libraries, airports, and schools. There are everywhere! Virtually every wireless USB card is compatible with Wi-Fi. It's standard by now.
Unlike Wi-Fi, which allows you to keep connecting for a range of around 200 feet, wireless Internet service provided by cell carrier allows you to obtain wireless Internet service where your cell carrier provides coverage, and this provides much more coverage than 200 feet. If you want to gain access to the Internet via cell carrier network, you must pay a monthly fee for service. A standard data plan includes 5 GB. This is enough for surfing the Internet, using e-mail service, playing online games, watching short online video clips, but if you want to download massive files like movies, it's better to use Wi-Fi for this purpose.
You'll be able to use the card either with laptop or desktop computers. Using the card with a laptop gives you mobility. You'll be able to use Internet while and whenever you want. It's very important for people who travel for business.
A wireless USB card is compact, it's very easy to install it and it will start working quickly. Some models of cards have an external antenna, it allows the user to pick up a stronger signal.