A backpack offers a solution for various activities. This way, you not only take backpacks to school or work, but you can also use a backpack when you go out for a day. Before you buy a backpack, it's important that you decide what you want to use it for. For example, a bag of 10 to 25 liters is sufficient for a busy working day and you need a backpack of at least 20 liters if you take books and notebooks with you. Do you use the backpack while walking or cycling? Think of extra features, such as a ventilated back.