Backing:

The bottom layer of a quilt sandwich, or the backside of the quilt. Generally made of one solid piece of fabric, or several pieces sewn together to accommodate larger quilts.

Batting:

A layer of padding/insulation between the quilted top and the backing of a quilt. Can be made of cotton, polyester, wool, or other materials.  Batting comes in many thicknesses and styles, and should be chosen to suit your particular needs.

Binding:

A narrow strip of fabric that wraps around and covers the raw edges of the quilt. You can bind using either single fold, or double fold (french) binding.

Loft:

The thickness of a batting. Can range anywhere from a few millimeters up to 1/2″ thick or more.