What difference does the 'waterproof lining' mentioned in the bag description actually make when using it?

A waterproof lining means the fabric covering the «inside» of the bag keeps water out. Different from whether the outer fabric withstands rain, its role is to prevent moisture from soaking into the fabric when something inside leaks or spills.

The medium vase bag choco brown is stated to be resistant to contamination and scratches by using a waterproof lining^[1]. When the lining does not absorb water, if a tumbler lid opens slightly or a lotion cap becomes loose, stains do not spread and stay on the surface, making it easy to wipe off with a dry cloth. Typically, such linings have a smoothly coated surface, so even if angled items like keys or nail clippers roll around, threads do not easily scratch or pull loose.

Ultimately, rather than adding a completely new function, a waterproof lining is closer to preventing minor accidents inside the bag from leaving lasting traces. For someone who wants to carry it every day while worrying less about what they put inside, this single line is quite practical information.