Waterproof or water-resistant describes objects relatively unaffected by water or resisting the ingress of water under specified conditions. Such items may be used in wet environments or under water to specified depths. Waterproofing describes making an object waterproof or water-resistant (such as a camera, watch or mobile phone). “Water resistant” and “waterproof” often refer to penetration of water in its liquid state. Permeation of water vapor is reported as a water vapor transmission rate. The hulls of boats and ships were once waterproofed by applying tar or pitch. Modern items may be waterproofed by applying water-repellent coatings or by sealing seams with gaskets or O-rings.