A burner phone is a phone that can be “burned” or thrown away after use. It generally has no trace to the user and is purchased with cash or a gift card.
There are presently apps for many smart phones to create burner numbers. One such app is called “BURNERAPP” and can be used to have many numbers ringing to one device. This app is excellent for using to create quick numbers but is not as secure as having an actual phone.
There are companies that specialize in burner phones like, “Burner Phone” which for $75 USD you can have an actual anonymous burner phone shipped to you.