What is Left-Handedness?
A left-handed person is someone who uses their left hand more frequently and with greater ease than their right hand. The activity most commonly used to define a person’s handedness is handwriting. Left-handed people do not necessarily favor their left hand for all tasks, so the distiction is sometimes blurred. The fact that there is no strict, empirical definition for left-handedness leads to ambiguity regarding the percentage of left-handed people in the world.
Left-handed people normally integrate well into a predominantly right-handed world, but may have difficulty using products that are designed specifically for the right-handed population. Lefties may also possess unique mental characteristics due to the physiological differences in their brains. Humans have some degree of brain lateralization; certain mental functions are performed primarily in a particular hemisphere of the brain.1 The side of the brain in which a function (e.g. language) occurs is sometimes opposite between left- and right-handed people.
Studies show that left-handedness does not necessarily correspond with "left-sidedness" (such as using your left foot to kick with or having a dominant left eye). However, most most left-handed people tend to have "left-sidedness" as well.