In human biology, handedness is an individual's preferential use of one h known as the dominant h due to it being stronger, faster or more dextrous. The other h comparatively often the weaker, less dextrous or simply less subjectively preferred, is called the non-dominant hand. In a study from 1975 on 7,688 children in US grades 1-6, left handers comprised 9.6% of the sample, with 10.5% of male children and 8.7% of female children being left-handed. Overall, around 90% of people are right-handed. Handedness is often defined by one's writing h as it is fairly common for people to prefer to do a particular task with a particular hand. There are people with true ambidexterity , but it is rare—most people prefer using one hand for most purposes.