Wi-Fi Enabled Device:
A device which can connect to the Internet via wireless networks around it (Access Points, Hotspots) such as personal computer, video game console, mobile phone, MP3 player or personal digital assistant.
A wireless network which is to be used for anyone having a Wi-Fi enabled device and who 1) is within the range of the network 2) is allowed to use the Hotspot.
Free Wi-Fi Hotspots:
Some companies provide Wi-Fi free within their range.
Ad-hoc Mode in Wi-Fi communications (Client to Client):
Devices can communicate with each other directly without a router for example a Wi-Fi enabled laptop can communicate directly with another Wi-Fi enabled laptop.
In this mode, no router or access point is needed, miracle!
This mode is mainly used with multiplayer handheld game consoles, digital cameras.