The IEC standard 60529 is a standard for dust and water damage resistance originally published back in 2004 and updated several times since. The standards cover everything from cabinets for electrical equipment to boxes on utility poles.
Headphones can get damp from perspiration and outdoors rain is a hazard. The cable TV boxes on the utility poles gets no respect at all.
The IP means ingress protection. The first digit is solid protection and the second digit is liquid protection.
Mobile phones are often subject to many abuses. My iPhone 7 plus is rated IP67 which means it’s secure from dust in addition to being safe from drowning. More recent phones have become even more robust against the elements.
- IPX0 – No protection
- IPX1 – Protects from dripping water
- IPX2 – Protects from vertically dripping water
- IPX3 – Protects from sprays up to 60°
- IPX4 – Protects from splashing water, no matter the direction
- IPX5 – Protects from water jets at any direction
- IPX6 – Protects from powerful water jets
- IPX7 – Protects in water up to 3 feet (1 meter)
- IPX8 – Protects when immersed in water over 3 feet
The testing is done partially fore marketing reasons but also so that educated consumers can identify products more suitable to their lifestyle.