A "Defective pixel" is a phenomenon that occurs due to the characteristics of the LCD. It is not a defect.
Minute dots( bright dots and/or dark dots as seen above) may occur on a LCD. These dots are called Defective pixels (quoted from Wikipedia)". These dots may or may not stand out according to the colors displayed. It is a characteristic of LCDs and are not a defect and cannot be completely avoided with todays manufacturing technology.
A dot that is always lit even after display is turned off (all dots are turned off). It shows as a bright dot on black displays.
A dot that is always off unlit even after the display is turned on (all dots are turned on). It shows as either a black dot or dot of other colors other than white on a white display.
