Internet Protocol? No. Intellectual Property? No.
It stands for Ingress (or International) Protection and is used to rate the level of protection an electronic device has against elements such as dust and water.
The first internationally available “waterproof” phone arrived all the way back in 2005; costing $500 The LG CanU 502S was based on the Japan-only Casio G’zOne TYPE-R (we have no idea how to pronounce this either – “Gee Zone”? “Gee Zee One”? “Jeez One”?) it boasted a 1.3 MP camera and 2.2″ display. The first “waterproof” smartphone was actually the Nokia 5500 Sport, running the Symbian OS and sporting EDGE connectivity, it was quite a distance from the powerhouse devices we use today.
“Waterproof” smartphones really started to become popular after Sony released the IP57 rated Xperia Z in 2013.
Notice we are using quotation marks whenever we use the word “waterproof”. Many other terms are regularly used when describing a device that can take some liquid abuse; water-resistant, water-tight, water-repellent too name a few, but none of these give you any idea of the level of protection you are receiving. This is where the numerical part of the IP rating comes in.
The first number signifies the protection level against solid objects and ranges from 0 to 6, 6 being fully dust-tight. The second number signifies the level of protection against water (not beer, wine or urine!) and ranges from 0 to 8. 8 signifies continuous immersion of over 1 metre – the IP rating doesn’t actually specify how long for, or how deep past 1m the device can be submerged, this is different per manufacturer so be careful!