It will give access to your non wi-fi devices to the internet from anywhere in the house without the need to use Ethernet cables.
Simply connect the adaptor in the external USB port of your computer and the antenna technology build in the adapter will give you access to your wireless network.
The latest standard is 802.11 N, while the G routers are beginning to disappear.
The wireless USB Adapter is the perfect solution for those users who want to upgrade older computers to the wireless technology.
The one I use is Linksys WUSB600N now rebranded AE1000.
But you can choose a USB Network Adapter from several companies at different prices.
P.S. The Cisco WUSB600n or AE1000 drivers won't be found by default by windows xp, vista or 7, so you will have to install them from the CD before plugging it to the USB port