What is a hot spot?
Own words

Hotspot: A hotspot is a physical location where people can access the Internet, typically using Wi-Fi, via a wireless local area network (WLAN) with a router connected to an Internet service provider. ... While many public hotspots offer free wireless access on an open network, others require payment.

A hot spot is an area on Earth over a mantle plume or an area under the rocky outer layer of Earth, called the crust, where magma is hotter than surrounding magma. The magma plume causes melting and thinning of the rocky crust and widespread volcanic activity.

Explanation: MY own word's.

gravity causes stares to cluster i think so

if you're asking what comes out, it's steam.