A crossbody bag is a bag with a strap that can be passed around the shoulder (we can then speak of shoulder bag or sling bag), or around the neck. From this category come sub-categories such as satchels, which are small crossbody bags generally of modest shape, with a top handle and allowing to carry some everyday objects. The messenger bag is a rectangular bag that can carry books or computers for example. It is often said that the messenger bag has a flap but this is not for us a criterion of differentiation.