The blending jar (or blender pitcher) is part of a blender where all the ingredients are placed and blended. It is possible to have a glass jar, but the jars may be made of plastic as well. The jars typically have blades affixed to the bottom, and the entire blending jar can be inserted into the main blender assembly. Jars always have a lid on the top to prevent the contents of the blender from accientally decorating your kitchen with chopped up fruit or ice cream.