The term 'Knitter's Medium' refers to the material used by knitters to create their projects. The most common medium is YARN, which is a type of thread made from natural or synthetic fibers. YARN is available in a variety of colors, textures, and weights, and can be used to make a wide range of items such as sweaters, hats, scarves, and blankets. Knitters use needles to manipulate the YARN into patterns and shapes, and the finished product can be used for decoration, clothing, or even toys.