Most hostels have lockers for your backpack — however, most of the time your backpack only holds your clothes, toiletries and dirty laundry which aren’t very likely to be stolen. Most of us carry anything valuable with us. Cash, plastic, passport in a money belt and camera, phone, Ipod, etc. (the fewer of these types of things you have, the better, IMO) in day pack, messenger bag, etc.

you can find backpacks with seperated top compartments that can be detached and worn as hippacks also. really convenient.

Thank you for your help. My backpack I bought has a detachable backpack that I can use during the day. So once you check into your hostel, most people just leave their bags with clothes in the room or in the hostel locker?

Aumuller: Yes: the consensus is that most people take their valuables (cameras, passport, wallet, money, etc.) with them in some sort of day pack and leave your hiking pack with only your cloths in the hostel I would say preferably in a locker. Although it’s highly unlikely anyone will mess with your cloths.