IP rating, or Ingress Protection rating, is a standard used to define the level of protection that a device, such as a smartphone or electronic gadget, has against intrusion from dust and water. The IP rating is typically represented by the letters "IP" followed by two digits. Here’s what each digit signifies:

1. First Digit (Protection against solids like dust):

   • 0: No special protection.
   • 1: Protection against solid objects greater than 50mm (e.g., accidental touch by hands).
   • 2: Protection against solid objects greater than 12.5mm (e.g., fingers or similar objects).
   • 3: Protection against solid objects greater than 2.5mm (e.g., tools, thick wires).
   • 4: Protection against solid objects greater than 1mm (e.g., small tools, wires, etc.).
   • 5: Partial protection against dust (limited ingress, no harmful deposit).
   • 6: Complete protection against dust (dust-tight).

2. Second Digit (Protection against liquids like water):

   • 0: No special protection.
   • 1: Protection against vertically falling drops of water (e.g., condensation).
   • 2: Protection against direct sprays of water up to 15 degrees from vertical.
   • 3: Protection against direct sprays of water up to 60 degrees from vertical.
   • 4: Protection against water sprayed from all directions - limited ingress permitted.
   • 5: Protection against low-pressure jets of water from all directions - limited ingress permitted.
   • 6: Protection against powerful jets of water (e.g., ship deck) - limited ingress permitted.
   • 7: Protection against the effects of immersion in water up to 1 meter deep for 30 minutes.
   • 8: Protection against continuous immersion in water under conditions specified by the manufacturer.

For example, an IP68 rating is common in high-end smartphones today, indicating complete protection against dust (6) and the ability to withstand immersion in water beyond 1 meter depth for a specified time (8).

When considering IP ratings, it's important to note that higher numbers generally indicate better protection. However, the specific conditions under which the device was tested should be considered for a complete understanding of its environmental durability.