Are you asking about the need or what is needed.
If it's what is need:
- the need is so that you don't spend much time & effort wiring the place with cables
- also so there is flexibility for the user. They're not restricted to 1 work station. They can move around the offices
If it's what is needed:
- a Wireless Access Point (WAP)sometimes referred to as a router. This gadget will connect the wireless clients in the network.
If you need the users to access the internet then this WAP will take in an RJ45 Ethernet cable from the internet and distribute to the wireless clients. This WAp can be 802.11 a/b/g but the latest is 802.11n which can handle more bigger data transfer speeds.
- A laptop with wireless capabilities. Preferably one which can handle 11 b/g/n.
- If users have desktops then you will need to buy wireless PCI cards to put into the PCI slots of the desktops. Ensure you buy the right profile cards as some traditional big cards won't fit into small factor PCs
- Some basic knowledge of the 802.11 protocol so that you can secure the Wireless LAN against unauthorized access. Otherwise the wireless internet will be abused by outsiders.