So let's start from the basics: IP is the acronym of ingress protection and it identifies the "protection" against humidity and suspended particles. The IP level is described by two figures: the first one is referred to the protection level against dust (including pollution), the second against water.

The ingress protection level is an international standard and it is utilized to measure the waterproofness of any electronic device. Products with a higher IP level keep the internal components safer and cleaner, while lower IPs means that the device might be water and dust sensitive.

This ingress protection level is particularly important when the giant screen is meant for outdoor use - while it became almost insignificant for indoor applications, where there is no risk of rain and pollution.

So you are probably wondering what is the exact definition of IP65? Here we go:
*6 (Dust) Dust-tight. No ingress of dust.
* 5 (Water) Protected against water jets. Water projected from a nozzle against the enclosure from any direction shall have no harmful effect.

Now, if you are curious about the IP rate, you could also ask: how can the screen be dust-tight if you have a forced ventilation system? Wouldn't the dust enter together with the air?

In the LED giant screens industry, the IP rate is usually referred to the front side (not the rear side) of the screen, which is most exposed to the atmospheric agents, and is therefore more likely to be stressed.

Please note that this information is not clearly stated by all LED giant screens manufacturers: some of them do not specify it on their brochures or websites that the IP65 is referred only to the front, not to the rear.

Indeed the protection level on the rear side is usually lower, at IP64. LED screens with IP63 or lower should not be used in outdoor environment, so when evaluating different manufacturers, please make sure you double-check with them what is the rear side IP rate.

Remember, you could test their honesty and professionalism by asking: "How can the module be dust-tight if you have a forced ventilation system? Wouldn't the dust enter together with the air?" - and then see how they answer you.