Phones that come with low cost prepaid no contract plans, and are boxed to sell from a display rack in a department store, but can also be purchased online. “Burner” because you can set them up with no personal details- popular for criminals, teenagers, etc.

I honestly don’t understand why anyone would not use prepaid plans- I use visible for example, and it has full unlimited data on the Verizon network for $25/mo with an iphone that cost me under $200. It doesn’t seem in any way inferior to a high priced contract plan to me.