What Causes Dead Pixels (and How to Avoid Creating Them)

Each pixel has red, green, and blue sub-pixels driven by tiny transistors. When something interrupts that, the pixel fails.

Common causes

Manufacturing defects — a faulty transistor from the factory. Most day-one dead pixels are this.
Physical pressure — pressing hard on the panel, a tight laptop lid, or a heavy object in a bag.
Heat and humidity — extreme conditions degrade the liquid crystal and electronics.
Age — sub-pixels can fail gradually over many years.
Manufacturing dust — sometimes mistaken for a dead pixel; it sits under the glass and doesn't change with color (test with the White Screen).

Never press hard on the screen — clean with a dry or barely damp microfiber cloth.
Don't stack heavy items on a laptop lid.
Avoid leaving devices in hot cars.
Use a padded sleeve for transport.

Run the Dead Pixel Test when a device is new (while under warranty) and occasionally after — catching problems early gives you the most options.