Back-packs, sacks and other storage containers are useful for HOLDING your growing collection of commodities and personal possessions, but they are not automatically thief-proof.
Your inventory will likely become rather full of objects and it will be necessary for you to invest in containers like strong-boxes to keep items safe, and better yet, worn containers like backpacks so you can carry more without becoming overly weighed down. If you are too weighed down you will have trouble finding a steed large enough to bear you and will endure more damage when you tumble, move around more slowly, etc.
Shows you a summary of how much you are holding your inventory, how many items, and letting you see at a glance the weight stashed away in your containes including those worn about your person.
Check out the shops and stalls for items like backpacks and sacks and make sure you have precious containers well protected since losing just one item (in such a case) can deprive you of a world of possessions.