Wi-Fi is an open or secured wireless network (a place where you can easily access the internet while not being 'tethered' in place), HotSpots are access points that allow you to access the internet. (Coffee shops use Wi-Fi to become HotSpots so that their customers can browse the internet at their leisure). Blu-tooth allows you to pair your devices to one another to enable file sharing, communication etc. wirelessly. (ie. Wireless headsets are blu-tooth enabled, and most Macs can use blu-tooth technology to pair to android devices to share files, music etc if you don't feel like using cloud technology)