Organisations that run archery competitions have set out formal definitions for the various classes; many definitions of the longbow would exclude some medieval examples, materials, and techniques of use. Some archery clubs in the US classify longbows simply as bows with strings that do not come in contact with their limbs. According to the British Longbow Society, the English longbow is made so that its thickness is at least (62.5%) of its width, as in Victorian longbows, and is widest at the grip. This differs from the Medieval longbow, which had a thickness between 33% and 75% of the width. Also, the Victorian longbow does not bend throughout the entire length, as does the medieval longbow.