Running is a means of terrestrial locomotion allowing humans and other animals to move rapidly on foot. It is simply defined in athletics terms as a gait in which at regular points during the running cycle both feet are off the ground. This is in contrast to walking, where one foot is always in contact with the ground, the legs are kept mostly straight and the center of gravity vaults over the stance leg or legs in an inverted pendulum fashion. A characteristic feature of a running body from the viewpoint of spring-mass mechanics is that changes in kinetic and potential energy within a stride occur simultaneously, with energy storage accomplished by springy tendons and passive muscle elasticity. The term running can refer to any of a variety of speeds ranging from jogging to sprinting.
The ancestors of mankind developed the ability to run for long distances about four and a half million years ago, probably in order to hunt animals. Competitive running grew out of religious festivals in various areas. Records of competitive racing date back to the Tailteann Games in Ireland in 1829 BCE, while the first recorded Olympic Games took place in 776 BCE.
A school uniform is an outfit—a set of standardized clothes—worn primarily for an educational institution. They are common in primary and secondary schools in various countries (see list of countries below). When used, they form the basis of a school's dress code. Traditionally school uniforms have been largely subdued and professional. Boys' uniforms often consist of dark short or long trousers and a light-colored shirt, often with a tie. Girls' uniforms vary greatly between countries and schooling systems, but typically consist of a dress or a blouse worn either with a skirt or culottes or under a pinafore; some countries allow girls to wear trousers. The use of a blazer or suit-like jacket for either gender is also fairly common, especially in countries with relatively cold weather. While some countries have school uniforms that are essentially standard in all schools using it, others have each school with an individual uniform, varying in and often making use of badges.