AA product is recognised as waterproof when it has the ability to stop rain getting through, thus protecting the hiker from bad weather. It is worth knowing that there are different levels of impermeability, and different tests to measure them. On the one hand, we consider the impermeability of a fabric, while on the other, we prove the impermeability of an entire product. Check that in addition to using a waterproof material, your jacket has waterproof zips.