Workstations manufactured in the 1990s and early 2000s, before Wi-Fi became prevalent, often lack wireless networking cards or adapters that enable a computer to detect and interpret Wi-Fi signals.
If you want to bring wireless networking to your desktop or have an older, 802.11n-equipped laptop that you want to update with 802.11ac capability, the $98.99 Trendnet AC1900 High Power Dual Band ...