The Marvell Libertas 802.11g Wireless LAN Client Adapter - USB is a wireless network adapter that uses the Marvell Libertas chipset, supporting the 802.11g Wi-Fi standard. It's typically used for providing wireless internet or network access to computers through a USB connection.

The Windows driver for this device enables the operating system to communicate with the adapter, allowing the computer to use the wireless network functionality. Without the correct driver, your wireless adapter may not function properly or may not be recognized by your system.