The classification system for the sealing effectiveness of the enclosure of electrical and electronic equipment againts the ingress into the equipment of foreign bodies e.g. dust, moisture, tools, fingers etc. uses the letters IP (ingress protection) followed by two or three digits. An X is used in place of a digit if there is only one classification e.g. IPX4 (which only addresses resistance to moisture). The IP rating is particularly important when choosing an outdoor camera or webcam.
The first digit of the IP code indicates the degree that persons are protected against contact with moving parts (other than smooth rotating shafts, etc.) and the degree that equipment is protected against solid foreign bodies intruding into an enclosure.
The second digit indicates the degree of protection of the equipment inside the enclosure against the harmful entry of various forms of moisture (e.g. dripping, spraying, submersion, etc.)