A messenger bag (also called a courier bag) is a type of sack, usually made out of some kind of cloth (natural or synthetic), that is worn over one shoulder with a strap that goes across the chest resting the bag on the lower back.[1] While messenger bags are sometimes used by couriers, they are now also an urban fashion icon. Some types of messenger bags are called carryalls.[2] A smaller version is often called a sling bag.