A courier bag is usually made out of some kind of cloth which is worn over one shoulder with a strap that goes across the chest resting the bag on the lower back. While these are sometimes used by couriers, they have become a real fashion statement in many parts of the world. A smaller size is often called a sling bag, used while trekking or traveling.
This design of bags have been used in the transportation of mail and goods by different types of messengers, postal workers and bicycle couriers. Some Royal Mail carriers in the United Kingdom currently use large messenger bags to deliver mail.
The design of the modern messenger bag traces its origin to the utility bag of the 1950s made by De Martini Globe Canvas Company. Founded by Frank De Martini with his two daughters, Kathleen and Marge, the bags were originally allowed for linemen to carry any kind of necessary tools while climbing poles.
Globe Canvas eventually supplied bags to New York messenger firms all around in 1970s and 1980s. The larger messenger firms required riders bags and also paid a deposit for them. Bags were often customised for different firms. The two largest companies during those times were – Mobile Messenger and Can-Carriers, who used red and blue bags respectively.
In 1984, John Peters redesigned the De Martini bag using nylon, buckles and colorful stripes. He finished the bags with edge binding which set the stage for the craze of courier bag manufacturers. His designs are now the industry standard for all modern courier bags. These were the industry's first bags using technology to make it.
Similar in function to backpacks, these ensure comfort to people carrying heavy or bulky items, while allowing easy access to the stuff inside easily.
They typically incorporate features that make them particularly suitable for cycling, trekking or any other adventure activities. Fittings make it easy to move the shoulder strap. Also, provision of quick release buckles and an adjustable hinged buckle allow for easy opening of the bag. The ability to attach accessories, such as phone holsters, U-locks or even water bottles allows for a more convenient usage of the bag. The stabilizing straps help to prevent the bag from slipping while riding.
Courier bags are a style statement on their own. Usually both the genders use these bags but it is often the men who find more of a fashion statement apart from wallets and backpacks.