Overheating can cause damage to a laptop's LCD screen, but if everything is working properly, it shouldn't be an issue. Extreme temperature changes are a known cause of laptop screen cracking, though it's rare. To avoid this, it's best to use your laptop at room temperature. Other causes of screen cracking include closing the laptop cover when something is stuck between the keyboard and the screen, or pressure building up in a bag when the laptop is stored for long periods of time with other items.
Opening the laptop cover too forcefully can also put tension on the laptop screen and cause damage. Dropping heavy objects on your laptop, stepping on it, or sitting on it are some of the main causes of internal screen cracking. Small internal cracks can be repaired with special liquid adhesives used on optical panels to hold them together. I've asked around online and heard that the only thing that can cause a laptop screen to break is a sudden change in temperature.
Even if the damage to the laptop screen seems minor, such as dead pixels or lines crossing the screen, prolonged use will worsen it over time since every time you open the cover, the already compromised screen is further stressed and exposed to heat and electricity during operation. To confirm a broken screen internally, connect your laptop to an external display like a TV using an HDMI or VGA cable. The hinge on a laptop is closely related and often the root cause of problems with the LCD or laptop screen. Different resolutions and proportions will affect the pixel count; check with your manufacturer for your laptop's resolution.
It's not your fault if there's a crack in the screen; it's likely not caused by a fall since the screen would have broken instead of having a diagonal crack. To test this, connect your laptop to a working external monitor and see if the same issues persist; this will help you determine if it's due to the screen or other hardware like the GPU (graphics processing unit). Cracks on the laptop screen can occur when you close and open it quickly or hold it next to the screen. With technology improving, newer versions of screens for laptops and TVs offer sharing options via WI-FI or Bluetooth.
Different sizes can be measured using a ruler or measuring equipment by measuring diagonally across the screen.