What's a hot spot?
A hotspot is a physical location where people may obtain Internet access, typically using Wi-Fi technology, via a wireless local area network (WLAN) using a router connected to an internet service provider.
Put another way it's portable because it taps into 3G and/or 4G cellular networks, just like a smartphone does, and then wirelessly shares its data connection with other nearby (within 30 feet or so) Wi-Fi-enabled gadgets—typically, between three and 8 depending on the device and the carrier.
What good are they and why would I want one?
You can create 'hot spots' with a device you purchase (see below) or you can create one using your iPhone and certain equipped iPads.
I have an iPhone. Can I use that as a "hotspot"? The Short answer is yes. Go to >settings>Personal Hotspot>
How about using an iPad to create a hotspot? Again the short answer is yes, if you have a data plan on the iPad. If you don't know what this is you probably don't have one. But, if you create a hotspot on your phone, you can connect with your iPad!