WLAN, or wireless local area network, is often referred to as WiFi, 802.11, and simply "wireless." WiFi (aka. 802.11 a/b/g), is actually a protocol for a LAN. WiFi set a standard for how to use and connect through a LAN.
No additional equipment needed
WiFi is already built into most of today's notebooks, eliminating the need for a separate wireless card. Even better, there are notebook models available with built-in wireless broadband access, which is delivered through partnerships with cell phone carriers.