A good backpack is an essential part of any walkers equipment. Ideally it will be lightweight, compact, comfortable and sturdy. Preferably with plenty of storage space for your stuff.
A 30-litre backpack is ideal for day trips, but also comes in handy during a city trip. For hikes and backpacking, you need a backpack with a capacity of up to 50 litres or more on your shoulders, depending on what you want to take on the road.