The IP Code often called Ingress Protection Rating (but correctly the International Protection Rating) of a product is a classification that indicates how well the product resists intrusion of solids (such as dust) and liquids (such as water).
The first digit is the rating for Solids:
LEVEL 0 -- No protection against ingress of objects, even large objects such as fingers.
LEVEL 1 -- Objects larger than 50 mm cannot intrude.
LEVEL 2 -- Objects larger than 12.5 mm cannot intrude, e.g. fingers.
LEVEL 3 -- Objects larger than 2.5 mm cannot intrude, e.g. most small tools.
LEVEL 4 -- Objects larger than 1.0 mm cannot intrude, e.g. most small wires and screws.
LEVEL 5 -- Ingress of dust is prevented sufficiently to prevent it from interfering with product operation.
LEVEL 6 -- Dust tight.
The second digit is the rating for Liquids:
LEVEL 0 -- Not protected against liquids.
LEVEL 1 -- Dripping water (vertically falling drops) will have no harmful effect.
LEVEL 2 -- Dripping water has no harmful effect even if the product is tilted up to 15% relative to its normal position.
LEVEL 3 -- Spraying water(water falling as much as 60 degrees off vertical) has no harmful effect.
LEVEL 4 -- Splashing water will have no harmful effect, regardless of the direction it hits the product.
LEVEL 5 -- Water jets projected from a 6.3 mm nozzle against the product's enclosure from any direction will have no harmful effects. The test is done for 3 minutes involving 12.5 litres per minute at 30 kN/m^2 from a distance of 3 meters.
LEVEL 6 -- Powerful water jets from a 12.5 mm nozzle will have no harmful effect regardless of the direction of impact on the product enclosure.
LEVEL 7 -- The product is protected against immersion in water up to 1 meter below the surface for 30 minutes.
The ratings give the overall idea of the rating omit some specifics of the precise test conditions. So, for example, the reader is advised that if the product is rated LEVEL 4 against liquids, it may stand up to water but perhaps not some other liquid. It may also stand up to water for 15 minutes but not 20 minutes. If the reader has a bad case of insomnia, he/she should look up the specific details of the IP Code for a better understanding than we have been able to present here.
REAL WORLD EXAMPLE:
The IsatPhone PRO is rated IP54. The first digit 5 means that it is protected against dust and dust may enter its enclosure but cannot interfere with its operation but can enter. The second digit 4 means it can withstand splashing at least within the bounds of the internationally accepted test conditions.