Shoulder bags are practical to use because they allow you to keep your hands free and your stuff easily accessible. They also come in a variety of sizes and shapes which makes them ideal for both men and women.
They are also practical because they can hold a lot of things and they don't require you to carry your bag on your shoulders at all times.
The most noticeable difference between shoulder bags and other types of bags is that they do not require you to carry them on your shoulders at all times as backpacks do.