If you know which features you are looking for in a backpack, you will be able to find a hiking backpack that is suitable for your needs.
There are several types of backpacks for hiking: the difference is not only in size but also in the features that you find in each backpack that makes each one perfect for special use. You may check reviews for backpacks online at thriftyhiker.com/3f-ul-gear-backpack-review/.
These are some of the features you are looking at:
Many backpacks have an integrated plastic hydration bag or have suitable space for carrying water bags with holes for drinking tubes attached.
There are no backpacks that are 100% waterproof and this word is often misused: materials, pockets, different shapes, and other factors make it somewhat impossible to make a backpack that is truly waterproof.
Some backpacks have a waterproof cover that you use to wrap your entire backpack by putting it in a waterproof bag. This might sound a strange solution but it will actually make your backpack waterproof during a storm.
This part connects the upper part of your body to the backpack. The bigger the backpack, the softer, softer and wider the strap should be. The straps on most backpacks have a chest belt to keep the backpack tight to your body, relieving pressure from your shoulders and from your back.
Each backpack has an external cable which is useful for fixing additional equipment to the backpack such as climbing poles. The position of these cables can vary from one package to the next.