The Kindle Fire (KF) is a Kindle e-reader that is tied to the Amazon ebook ecosystem. Based on a customized Android operating system, the KF comes in several sizes and sports a full-colour, touch-enabled interface screen. Because of the faster specifications of the internal hardware, one can use the KF to watch movies, hop on to YouTube, and install pre-approved Android apps. It also works well as a small gaming platform.
I own two different versions for my personal use, and I also have a couple of brand-new ones still in their original packaging. I'm not collecting them, although one could make that case considering that I have a version of every Kindle they produced. The smallest KF is inexpensive, to the point where I use them as giveaway prizes when I sell my books at conventions. Before I put a new (self-pubbed) ebook up on Amazon, I go through and verify there are no issues on all of the platforms. My trad-pubbed books I get no say in, so I just assume they all work correctly until someone tells me about problems via email or after I'm on a convention panel.
Because the KF works so well with video, I consider them more of an Amazon Prime or YouTube front-end. I personally use a Kindle Paperwhite when I'm reading for pleasure. The KF has a shiny, reflective screen which is harder to read, whereas the Paperwhite has a textured, non-glare screen that is easy on the eyes.
Amazon offers a specialized Kindle Fire with a thick rubber shell made just for kids. You can lock out some functions, but any kid will soon learn how to access the volume and turn off the screen lock. Kids can use them as personal streaming devices so they can watch Trash Truck or Cocomelon all day. The children learn how to be a good little consumer while zoning out on the couch.