The shoulder bag is the most fundamental handbag silhouette: a bag with a single strap designed to sit on one shoulder. The category is almost infinitely broad — it includes structured boxes, slouchy soft bags, compact zip-top bags, and open-top everyday styles. Most bags with a single strap that isn't long enough to cross the body are technically shoulder bags.
For collectors, the 'shoulder bag' label often describes the mid-range workhorse: large enough for a full day's carry, structured enough to look polished, casual enough for most occasions. The Prada Galleria, Chanel Classic Flap with its chain worn on one shoulder, and the Celine Luggage are all shoulder bags by this definition.
Shoulder Bag vs. Crossbody
The strap length is the dividing line. A shoulder bag's strap puts the bag at hip height when worn on one shoulder; a crossbody strap is long enough to cross the body entirely. Many bags include both strap lengths, making the wearer's choice the deciding factor.