Individual difference is a universal phenomenon. It is said that no two individuals are exactly alike.They differ from each other in some way or the other. Such a similarity or difference between persons reveals individual differences.
According to Drever James
Individual Differences are variations or deviations from the average of the group, with respect to the mental or physical characters, occurring in the individual member of the group.
According to Carter B. Good
Individual Difference is the the variation or deviations among individual in regard to a single characteristics or a number of characteristics, those differences which in their totality distinguish one individual from another.
According to Skinner, C.E.
Today we think of individual differences as including any measurable aspect of the total personality.
According to R.S. and Marquis , D.G.
Individual differences are found in all psychological characteristics physical mental abilities, knowledge, habit, personality and character traits.