The HP WLAN 802.11bg W400 Windows driver is a software package that enables your Windows computer to communicate with an HP WLAN (Wireless Local Area Network) 802.11bg adapter, specifically the W400 series wireless network card. This driver allows the computer to connect to Wi-Fi networks, enabling wireless communication and internet access. The "802.11bg" part of the name indicates that the wireless card supports the 802.11b and 802.11g standards for Wi-Fi, which are common older standards, with 802.11g being faster than 802.11b.

The W400 wireless card is typically found in certain HP laptops, and the driver helps the operating system recognize and use the wireless card to connect to available Wi-Fi networks.