What are common LED polarity mistakes?

What are common LED polarity mistakes, common LED polarity mistakes include connecting LED backwards with anode and cathode swapped causing LED not to light, as LED is diode allowing current one direction only, with reversed polarity resulting in no light. Other common mistakes include connecting LED strip backwards where positive and negative reversed causing strip not to work, confusing long leg as anode and short leg as cathode, with beginners often connecting short leg to positive, which is wrong, as long leg is anode positive and short leg is cathode negative. Another mistake is not using resistor with LED causing burnout even with correct polarity, or using wrong voltage causing reverse breakdown if polarity reversed. Mistakes include connecting RGB LED strips with wrong polarity for common anode vs common cathode, causing colors not to work, and connecting LED to AC without rectifier causing reverse polarity half cycle damage. Also mistake of connecting multiple LEDs in parallel without considering polarity of each, causing some not to light. So common LED polarity mistakes are reversed anode cathode, swapping positive negative leads, mixing up long and short legs, confusing common anode with common cathode in RGB strips, and not checking polarity markings on LED strip, all causing LED not to light or be damaged, requiring correct polarity check with multimeter or datasheet.